glsl/linker: Fix unmatched TCS outputs being reduced to local variable
Always match TCS outputs since they are shared by all invocations within the patch and should not be converted to local variables.
This is one of the issues found in Downward.
Also sent a Piglit test to reproduce the issue.
The commit passes Intel CI: https://mesa-ci.01.org/global_logic/builds/50/group/63a9f0ea7bb98050796b649e85481845 (one failure in unrelated test)
Signed-off-by: Danylo Piliaiev firstname.lastname@example.org