glsl: fix bogus layout qualifier warnings

Print out GL_ARB_explicit_attrib_location warnings only
when parsing attribute that uses "location" qualifier.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77245
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>
Cc: "10.1 10.2" <mesa-stable@lists.freedesktop.org>
1 file changed