Mac’s OpenGL version is furthest away from our target of GL 3.2. This
commit brings Mac closer to other platforms, so that our shaders and
other code don’t diverge too much during development.
According to Apple’s OpenGL matrix these useful extensions are
available on all GPUs that will be able to run Blender 2.8.
Only checked in debug builds; we might need something more forceful.
Part of T49012
Mike Erwin
32757d488f