Source code for cygwin1.dll is available under the GPL license here:
ftp://ftp.cygwin.com/pub/cygwin/release/cygwin/cygwin-1.5.25-15.tar.bz2

Source code for freeglut.dll is available under the X-Consortium license here:
http://prdownloads.sourceforge.net/freeglut/freeglut-2.6.0-rc1.tar.gz

Links to the source code for glu32.dll and SGI license are available here:
http://www.geocities.com/vmelkon/glu.html
http://oss.sgi.com/projects/ogl-sample
