Initial structures to bridge the shader's use of particular builtins to
behavior of the "fixed function" logic wrapped around it.

Bug: b/120799499

Change-Id: I5cb360909c62615efab2e500f5c24109737e4ab7
Reviewed-on: https://swiftshader-review.googlesource.com/c/23709Tested-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>