i965/sf: Consult brw_wm_prog_data when setting up SF/SBE state.

i965/sf: Consult brw_wm_prog_data when setting up SF/SBE state.

Previously, the SF/SBE setup code delivered varying inputs to the FS
in the order in which they appear in the gl_program::InputsRead
bitfield, since that's what the FS expects.

When we add support for more than 64 varying components, this will no
longer always be the case, because the Gen6+ SF/SBE stage is only
capable of performing arbitrary reorderings of 16 varying slots.  So,
when there are more than 16 vec4's worth of varying inputs, the FS
will have to adjust the order its input varyings in order to partially
match the order of outputs from the geometry or vertex shader.

To allow extra flexibility in the ordering of FS varyings, this patch
causes the SF/SBE to deliver varying inputs to the FS in exactly the
order that the FS requests, by consulting brw_wm_prog_data::urb_setup
and brw_wm_prog_data::num_varying_inputs.

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