anv: Build the real pipeline layout in the pipeline

anv: Build the real pipeline layout in the pipeline

This gives us the chance to pack the binding table down to just what the
shaders actually need.  Some applications use very large descriptor sets
and only ever use a handful of entries.  Compacted binding tables should be
much more efficient in this case.  It comes at the down-side of having to
re-emit binding tables every time we switch pipelines, but that's
considered an acceptable cost.