glsl/linker: fix bug when checking precision qualifier

glsl/linker: fix bug when checking precision qualifier

According to GLSL ES 3.2 spec, see table in 9.2.1 "Linked Shaders"
section, the precision qualifier should match for uniform variables.
This also applies to previous GLSL ES 3.x specs.

This 'if' checks the condition for uniform variables, while for UBOs
it is checked in link_interface_blocks.cpp.

Fixes: b50b82b8a553
("glsl/es31: precision qualifier doesn't need to match in shader interface block members")

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>