glsl: Reject illegal qualifiers on atomic counter uniforms.

glsl: Reject illegal qualifiers on atomic counter uniforms.

This fixes

dEQP-GLES31.functional.uniform_location.negative.atomic_fragment
dEQP-GLES31.functional.uniform_location.negative.atomic_vertex

Both of which have lines like

layout(location = 3, binding = 0, offset = 0) uniform atomic_uint uni0;

The ARB_explicit_uniform_location spec makes a very tangential mention
regarding atomic counters, but location isn't something that makes sense
with them.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>