i965/state: Clean up WM/PS state to pull more things out of prog_data

i965/state: Clean up WM/PS state to pull more things out of prog_data

Now that we have a persample_shading bit in prog_data we can reduce the
amount the state setup code needs to be looking at the GL state.  In
particular, it no longer pulls anything directly out of the
gl_fragment_program and no longer depends on NEW_FRAGMENT_PROGRAM.

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