This was confusing me for a while as it would simply fail to find the
proper support and I was confronted with a blank screen in certain areas.
This warning (and the associated change of default. I'd like users to see
warnings as well) will help others figure out why there is a blank screen.
My driver supports the necessary extensions (but not 4.3), so if I force it to
advertise 4.3 support (and glsl 420 support) it will properly render.
I tried to create a patch that only looks for the proper extension, and
it works for me, but I feel as though it would depend on behaviour that
most GL implementations would not implement the same way so I've put
it in a separate branch and probably won't request to merge it.
Mesa should get 4.3 support soon enough anyway, so it shouldn't
be an issue for much longer.
