glamor: add EXT_gpu_shader4 support
This enables a number of the GLSL 1.30 paths on GPUs that have EXT_gpu_shader4 but don't have GLSL 1.30 exposed.
(Intel gen4/5 mainly, when we finish crocus support for the ext)
This enables a number of the GLSL 1.30 paths on GPUs that have EXT_gpu_shader4 but don't have GLSL 1.30 exposed.
(Intel gen4/5 mainly, when we finish crocus support for the ext)