I am not sure what all you copied over from the autotools stuff, but CheckLib looks for libGL (not the OpenGL framework).
I was able to get it to compile and work by adding this line:
env.Append(CXXFLAGS=' -framework OpenGL')
and commenting out the exits in the GL and GLU checks. Somebody w/ more scons experience will need to find a better way to fix this. Can appleboy chime in on this?
For now if it works it works. I would add a check for "osx" which employs this override, similar to the compile time option for mingw. I'll do this in the release candidate when I get my computer put back together.