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.

Signed-off-by: Danylo Piliaiev <danylo.piliaiev@globallogic.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104297
(cherry picked from commit 9f29d903)