intel/cs: Make thread_local_id a regular builtin param

intel/cs: Make thread_local_id a regular builtin param

This is a lot more natural than special casing it all over the place.
We still have to do a bit of special-casing in assign_constant_locations
but it's not special-cased quite as bad as it was before.

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