intel/fs: Add INTEL_DEBUG=no32 debugging flag.

intel/fs: Add INTEL_DEBUG=no32 debugging flag.

This is useful in order to identify codegen issues caused by SIMD32.
It doesn't currently have any effect on compute shaders since SIMD32
dispatch is only enabled for CS when it's strictly necessary to do so
in order to support the workgroup size requested for the shader --
That might change in the future though when we hook up the SIMD32
heuristic to CS compilation.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>