main/cs: Add additional compute shader constant values

With MESA_EXTENSION_OVERRIDE=GL_ARB_compute_shader, this fixes piglit:
* arb_compute_shader-minmax

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
glsl/cs: Add several GLSL compute shader variables

With MESA_EXTENSION_OVERRIDE=GL_ARB_compute_shader, this fixes piglit:
built-in-constants tests/spec/arb_compute_shader/minimum-maximums.txt

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>