i965/compute: Skip SIMD8 generation if it can't be used
i965/compute: Skip SIMD8 generation if it can't be used

If the local workgroup size is sufficiently large, then the SIMD8
program can't be used. In this case we can skip generating the SIMD8
program. For complex programs this can save a significant amount of
time.

Signed-off-by: Jordan Justen <a79006884ba9cf5f4f7fcbb92a15b208780d8c97@intel.com>
Reviewed-by: Matt Turner <789b315743a28dd066a4ba1459c35951c291d8a6@gmail.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler