GLEW stub test

GLEW functions don't show up in the current binding because they are hidden
behind function pointers and some #define tricks. Stuff that cgo doesn't really like. We can still use these if we stub them out in c. Go will use gcc to
compile c files then link the result. This is mostly a proof of concept, will
write a script to export all the functions so I don't end up doing this by
hand.