mesa: add const flags to skip MaxVarying and MaxUniform linker checks (v2)

mesa: add const flags to skip MaxVarying and MaxUniform linker checks (v2)

This is only temporary until a better solution is available.

v2: print warnings and add gallium CAPs

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>