- Remnants of old fixed function attributes all gone
- Initial support for some builtins to prove the model
- Setup now driven by correct shader state
- VS->FS intermediate structure matches SPIRV model -- builtins are not
in location space; location space itself is flat scalars rather than
vec4-oriented.

There are still some vertex pipe features which are not supported, as
ES3 didn't have them -- proper handling of noperspective, etc.

Change-Id: Ia8e3c72af54c4d1cbcc18482a741daa5e8e7c053
Bug: b/120799499
Reviewed-on: https://swiftshader-review.googlesource.com/c/24376
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Chris Forbes <chrisforbes@google.com>