i965/fs: Pass usage of depth, W, and sample mask through prog_data

i965/fs: Pass usage of depth, W, and sample mask through prog_data

We really need to stop pulling information directly out of shaders for
state setup.  For one thing, if we want any sort of an on-disk shader
cache, having all of this metadata in one place is going to be crucial.
Also, passing it all through prog_data cleans up the compiler <-> state
setup API substantially.

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