glsl: Distinguish "type mismatch" error messages for modulus operator.

glsl: Distinguish "type mismatch" error messages for modulus operator.

Previously, it would simply say "type error" in three different cases:
- The LHS is not an integer
- The RHS is not an integer
- The LHS and RHS have different base types (int vs. uint)

Now the error messages state the specific problem.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>