Test cases that uses compute shaders were exited when run on platforms
not supporting compute shaders. Since 4.0 Blender requires a platform
that supports compute shaders.
We should eventually phase out `GPU_compute_shader_support` as it
would always return true. Note that in OpenGL a platform is mentioned
that doesn't support compute shaders, but that is from an old driver
and should be save to remove as well.
Jeroen Bakker