mesa/glsl: sparse fixups
KHR-GL46.sparse_texture_clamp_tests.SparseTextureClampLookupResidency and KHR-GL46.sparse_texture2_tests.UncommittedRegionsAccess can't pass without them
KHR-GL46.sparse_texture_clamp_tests.SparseTextureClampLookupResidency and KHR-GL46.sparse_texture2_tests.UncommittedRegionsAccess can't pass without them