i965/fs: Make better use of the builder in shader_time
i965/fs: Make better use of the builder in shader_time

Previously, we were just depending on register widths to ensure that
various things were exec_size of 1 etc.  Now, we do so explicitly using the
builder.

Reviewed-by: Topi Pohjolainen <749697f19798b7f640b17221fd283b903825f071@intel.com>
Acked-by: Francisco Jerez <5906ff32bdd9fd8db196f6ba5ad3afd6f9257ea5@riseup.net>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler