i965/fs: Limit SIMD width of various virtual opcodes to the maximum supported value.
i965/fs: Limit SIMD width of various virtual opcodes to the maximum supported value.

Which is 16 or 8 in most cases.  This will make sure that 32-wide
virtual instructions get chopped up into chunks of their maximum
execution size.

Reviewed-by: Jason Ekstrand <68c46a606457643eab92053c1c05574abb26f861@jlekstrand.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler