GL_ARB_separate_shader_objects allows the application to mix-and-match
TCS and TES programs separately.  This means that the interface between
the two stages isn't known until the final SSO pipeline is in place.

This isn't a great match for our hardware: the TCS and TES have to agree
on the Patch URB entry layout.  Since we store data as per-patch slots
followed by per-vertex slots, changing the number of per-patch slots can
significantly alter the layout.  This can easily happen with SSO.

To handle this, we store the [Patch]OutputsWritten and [Patch]InputsRead
bitfields in the TCS/TES program keys, introducing program recompiles.
brw_upload_programs() decides the layout for both TCS and TES, and
passes it to brw_upload_tcs/tes(), which store it in the key.

When creating the NIR for a shader specialization, we override
nir->info.inputs_read (and friends) to the program key's values.
Since everything uses those, no further compiler changes are needed.
This also replaces the hack in brw_create_nir().

To avoid recompiles, brw_precompile_tes() looks to see if there's a
TCS in the linked shader.  If so, it accounts for the TCS outputs,
just as brw_upload_programs() would.  This eliminates all recompiles
in the non-SSO case.  In the SSO case, there should only be recompiles
when using a TCS and TES that have different input/output interfaces.

Fixes Piglit's mix-and-match-tcs-tes test.

v2: Pull the brw_upload_programs code into a brw_upload_tess_programs()
    helper function (requested by Jordan Justen).

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>