Fix opengl.py example on OS X
Fix opengl.py example on OS X

adamlwgriffiths/Pyglet,adamlwgriffiths/Pyglet,niklaskorz/pyglet,seeminglee/pyglet64,adamlwgriffiths/Pyglet,niklaskorz/pyglet,niklaskorz/pyglet,seeminglee/pyglet64,adamlwgriffiths/Pyglet,seeminglee/pyglet64,niklaskorz/pyglet