Parts of libextensions are taken from emx library sources:
The relevant excerpts of COPYING.emx are:

Copyright (c) 1990-1998 by Eberhard Mattes
GNU General Public License (GPL)
--------------------------------

emx is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

emx is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with emx; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. See \emx\doc\COPYING for details. You must not
change the existing Copyright notice.  If you modify a source file, a
notice to that effect must be added to the source file.
[...] The emx libraries are not distributed under the GPL.  Linking an
application with the emx libraries does not cause the executable to be
covered by the GNU General Public License.  You are allowed to change
and copy the emx library sources if you keep the copyright message
intact.  If you improve the emx libraries, please send your
enhancements to the emx author (you should copyright your enhancements
similar to the existing emx libraries).  Of course, all this does not
apply to the libraries which are distributed under the GPL or the GNU
Library General Public License (LGPL, see \emx\doc\COPYING.LIB) or the
BSD license (see \emx\doc\COPYING.BSD), such as termcap.a, gpp.a and
curses.a.

Code derived from code released by the University of California,
Berkeley, is released under the terms of \emx\doc\COPYING.BSD.  This
applies to the libraries `bsd', `btermcap', `curses', and `db'.

There is also a special exception for the GNU standard C++ library,
libstdc++, see \emx\doc\COPYING.SCP.  This applies to stdcpp.a and
stdcpp.lib.

You are allowed to use, copy, and change the programs in \emx\sample
if you keep the copyright message intact.  The test programs in
\emx\test are in the public domain.

Permission is granted to make and distribute verbatim copies of the
manuals written by Eberhard Mattes provided the copyright notice is
preserved on all copies.  If you modify those manuals, a notice to
that effect must be added to the manual.


Summary
-------

1. Redistributing emx and GNU programs

  If you redistribute emx and the GNU programs, you also have to
  redistribute the source code:

    emxdev1.zip, emxdev2.zip  ->  emxsrcd1.zip, emxsrcd2.zip
    emxrt.zip                 ->  emxsrcr.zip
    gnudev1.zip, gnudev2.zip  ->  gccsrc1.zip, gccsrc2.zip, gccsrc3.zip,
                                  gdbsrc1.zip, gdbsrc2.zip, gnusrc.zip,
                                  gbinusrc.zip
    gnuinfo.zip               ->  gnusrc.zip
    gppdev.zip                ->  gppsrc.zip, gccsrc1.zip, gccsrc2.zip,
                                  gccsrc3.zip
    gobjcdev.zip              ->  gccsrc1.zip, gccsrc2.zip, gccsrc3.zip

2. Distributing applications

  There are no copyright restrictions on applications created with the
  emx tools and the GNU C compiler and linked with the emx libraries.
  However, there are restrictions for applications linked with GNU or
  BSD libraries.

3. Distributing the emx runtime package

  If you distribute emxrt.zip, you also have to redistribute
  emxsrcr.zip.  If you electronically distribute an application which
  requires the emx runtime package, I recommend putting a pointer to
  emxrt.zip into the documentation instead of distributing emxrt.zip.
  That way, users usually get the latest version of emxrt.zip.

4. Distributing applications and emx.dll, emxio.dll and emx.exe

  For small programs, redistributing emxrt.zip may be inconvenient.
  You are allowed to distribute emx.dll, emxio.dll, and emx.exe with
  your application as long as emx.dll, emxio.dll, and emx.exe have not
  been modified.  You should include a notice in the documentation
  which tells users where they can get the complete emx package.

  Note that you can create stand-alone OS/2 applications (using the
  -Zomf -Zsys options of GCC) which do not need emx.dll.

5. Distributing modified copies

  If you modify an emx tool, the GPL will apply without exception,
  that is, you have to include full source code.  See COPYING for
  details.  If you distribute a modified emx.dll, please choose
  another name for the DLL to avoid compatibility problems.  For
  instance, if someone adds feature A to emx.dll, and someone else
  adds feature B to emx.dll, programs using feature A cannot be run
  simultaneously with programs using feature B because only one
  instance of any DLL can be active (either feature A or feature B
  will be present, but not both).  If the DLLs are named emx_a.dll and
  emx_b.dll, that problem does not arise.  The -E option of emxbind
  selects the name of the emx DLL to use.


Copyright
---------

The emx runtime and the emx development tools are

    Copyright (c) 1990-1996 by Eberhard Mattes.

emxfpemu (originally known as wm-FPU-emu) is

    Copyright (c) 1992-1994 by W. Metzenthen.

The emx C library is

    Copyright (c) 1990-1996 by Eberhard Mattes
    Copyright (c) 1991-1993 by Kolja Elsaesser
    Copyright (c) 1992-1993 by Steffen Haecker
    Copyright (c) 1992-1996 by Kai Uwe Rommel
    [...this place is reserved for your name...]

The emx graphics library, the emx video library and the emx OMFLIB
library are

    Copyright (c) 1987-1996 by Eberhard Mattes

DUEL has been written by Michael Golan and is in the public domain.

The GNU programs and libraries, including GCC, GAS, GDB, and libg++,
are

    Copyright (c) by Free Software Foundation, Inc.

The curses library (curses.a), the BSD C library (bsd.a), the BSD
database library (db.a), and the BSD termcap library (btermcap.a) are

    Copyright (c) by University of California, Berkeley


Files
-----

This is an incomplete overview over the executables and libraries.  It
is provided for your convenience only.  If the information in the
source code contradicts this table, the information in the source code
takes precedence.

For .lib and .obj files, see the corresponding .a and .o file,
respectively.

File                    | License       | Copyright owner     | Source ZIP
------------------------+---------------+---------------------+------------
\emx\bin\ar.exe         | GPL           | FSF                 | gbinusrc
\emx\bin\as.exe         | GPL           | FSF                 | gbinusrc
\emx\bin\cc1.exe        | GPL           | FSF                 | gccsrc[123]
\emx\bin\cc1obj.exe     | GPL           | FSF                 | gccsrc[123]
\emx\bin\cc1plus.exe    | GPL           | FSF                 | gccsrc[123]
\emx\bin\cpp.exe        | GPL           | FSF                 | gccsrc[123]
\emx\bin\emx.exe        | GPL+          | em                  | emxsrcr
\emx\bin\emxbind.exe    | GPL           | em                  | emxsrcd[12]
\emx\bin\emxcat.exe     | GPL           | em                  | emxsrcd[12]
\emx\bin\emxd.exe       | GPL+          | em                  | emxsrcr
\emx\bin\emxdoc.exe     | GPL           | em                  | emxsrcd[12]
\emx\bin\emxexp.exe     | GPL           | em                  | emxsrcd[12]
\emx\bin\emxfpemu       | GPL           | W. Metzenthen       | emxsrcr
\emx\bin\emxaout.exe    | GPL           | em                  | emxsrcd[12]
\emx\bin\emximp.exe     | GPL           | em                  | emxsrcd[12]
\emx\bin\emxinst.cmd    | GPL           | em                  | emxdev[12]
\emx\bin\emxl.exe       | GPL+          | em                  | emxsrcr
\emx\bin\emxload.exe    | GPL           | em                  | emxsrcr
\emx\bin\emxomf.exe     | GPL           | em                  | emxsrcd[12]
\emx\bin\emxomfar.exe   | GPL           | em                  | emxsrcd[12]
\emx\bin\emxomfld.exe   | GPL           | em                  | emxsrcd[12]
\emx\bin\emxrev.cmd     | GPL           | em                  | emxrt
\emx\bin\emxstack.exe   | GPL           | em                  | emxsrcr
\emx\bin\emxtsf.exe     | GPL           | em                  | emxsrcd[12]
\emx\bin\emxupd.exe     | GPL           | em                  | emxsrcd[12]
\emx\bin\gasp.exe       | GPL           | FSF                 | gbinusrc
\emx\bin\gcc.exe        | GPL           | FSF                 | gccsrc[123]
\emx\bin\gdb.exe        | GPL           | FSF                 | gdbsrc[12]
\emx\bin\gprof.exe      | BSD           | UCB                 | gbinusrc
\emx\bin\info.exe       | GPL           | FSF                 | gnusrc
\emx\bin\ld.exe         | GPL           | FSF                 | gbinusrc
\emx\bin\listomf.exe    | GPL           | em                  | emxsrcd[12]
\emx\bin\makeinfo.exe   | GPL           | FSF                 | gnusrc
\emx\bin\nm.exe         | GPL           | FSF                 | gbinusrc
\emx\bin\objdump.exe    | GPL           | FSF                 | gbinusrc
\emx\bin\pmgdb.exe      | GPL           | em                  | emxsrcd[12]
\emx\bin\size.exe       | GPL           | FSF                 | gbinusrc
\emx\bin\strip.exe      | GPL           | FSF                 | gbinusrc
\emx\bin\texi2dvi.cmd   | GPL           | em                  | gnuinfo
\emx\bin\texindex.exe   | GPL           | FSF                 | gnusrc
\emx\bin\touch.exe      | GPL           | em                  | emxsrcd[12]
\emx\bin\updt.exe       | GPL           | em                  | emxsrcd[12]
\emx\dll\emx.dll        | GPL+          | em                  | emxsrcr
\emx\dll\emxio.dll      | GPL+          | em                  | emxsrcr
\emx\dll\emxlibc.dll    | emx-lib       | em                  | emxsrcd[12]
\emx\dll\emxlibcm.dll   | emx-lib       | em and contributors | emxsrcd[12]
\emx\dll\emxlibcs.dll   | emx-lib       | em and contributors | emxsrcd[12]
\emx\dll\emxwrap.dll    | emx-lib       | em and contributors | emxsrcd[12]
\emx\dll\gppdemid.dll   | GPL           | FSF, em             | gnusrc
\emx\lib\bsd.a          | BSD           | UCB                 | bsdsrc
\emx\lib\btermcap.a     | BSD           | UCB                 | bsdsrc
\emx\lib\c_alias.a      | emx-lib       | em                  | emxsrcd[12]
\emx\lib\c_static.a     | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\curses.a       | BSD           | UCB                 | bsdsrc
\emx\lib\db.a           | BSD           | UCB                 | bsdsrc
\emx\lib\emx2.a         | emx-lib       | em                  | emxsrcd[12]
\emx\lib\emxio.a        | emx-lib       | em                  | emxsrcr
\emx\lib\g.a            | emx-lib       | em                  | emxsrcd[12]
\emx\lib\gcc.a          | emx-lib, GPL+ | em, FSF             | emxsrcd[12]
\emx\lib\gcc_p.a        | emx-lib, GPL+ | em, FSF             | emxsrcd[12]
\emx\lib\gpp.a          | LGPL          | FSF                 | gppsrc
\emx\lib\graph.a        | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\m.a            | emx-lib       | em                  | emxsrcd[12]
\emx\lib\moddef.a       | emx-lib       | em                  | emxsrcd[12]
\emx\lib\omflib.a       | emx-lib       | em                  | emxsrcd[12]
\emx\lib\os2.a          | emx-lib       | em                  | emxsrcd[12]
\emx\lib\os2_p.a        | emx-lib       | em                  | emxsrcd[12]
\emx\lib\regexp.a       | regexp        | Henry Spencer       | emxsrcd[12]
\emx\lib\socket.a       | emx-lib       | em                  | emxsrcd[12]
\emx\lib\stdpp.a        | GPL+          | FSF                 | gppsrc
\emx\lib\termcap.a      | GPL           | FSF                 | gnusrc
\emx\lib\tmalloc.a      | emx-lib       | em                  | emxsrcd[12]
\emx\lib\video.a        | emx-lib       | em                  | emxsrcd[12]
\emx\lib\wrap.a         | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\mt\c.a         | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\mt\c_app.a     | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\mt\c_dllrt.a   | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\mt\c_dllso.lib | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\mt\c_import.a  | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\mt\emx.a       | emx-lib       | em                  | emxsrcd[12]
\emx\lib\mt\malloc1.a   | emx-lib       | em                  | emxsrcd[12]
\emx\lib\mt\objc.a      | GPL+          | FSF                 | gccsrc[123]
\emx\lib\mt\sys.lib     | emx-lib       | em                  | emxsrcd[12]
\emx\lib\st\c.a         | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\st\check.a     | GPL           | Richard W.M. Jones  | gccsrc[123]
\emx\lib\st\c_app.a     | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\st\c_app_p.a   | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\st\c_dllrt.a   | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\st\c_dllso.lib | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\st\c_import.a  | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\st\c_p.a       | emx-lib       | em and contributors | emxsrcd[12]
\emx\lib\st\emx.a       | emx-lib       | em                  | emxsrcd[12]
\emx\lib\st\malloc1.a   | emx-lib       | em                  | emxsrcd[12]
\emx\lib\st\objc.a      | GPL+          | FSF                 | gccsrc[123]
\emx\lib\st\sys.lib     | emx-lib       | em                  | emxsrcd[12]


Legend:

BSD     BSD license (see \emx\doc\COPYING.BSD)
em      Eberhard Mattes
emx-lib emx library, see above
FSF     Free Software Foundation, Inc
GPL     GNU General Public License (\emx\doc\COPYING)
GPL+    GPL with special exceptions
LGPL    GNU Library General Public License (\emx\doc\COPYING.LIB)
regexp  see \emx\src\regexp\COPYRIGH
UCB     University of California, Berkeley


------------------------- END OF COPYING.EMX ------------------------------- */