Updates to SGI GLU code to get it to compile clean with the Open Watcom compiler.

Updates to SGI GLU code to get it to compile clean with the Open Watcom compiler.
Most of the changes were to get rid of warnings, but many of the warnings could
not be removed in the code so I also added #pragma's to disable the warnings.
Someone really should clean up this code, but I didn't want to mess with it
that much (and potentially break it).