i965: Move the entire compiler API into a single file

i965: Move the entire compiler API into a single file

At this point, the compiler API has been substantially simplified.  In the
spirit of Kristian's making a compiler library, this commit makes a single
header file that contains, more-or-less, the entire compiler API.

There's still a bit of cleanup to do particularly in the area of geometry
shaders.  However, this gets us much closer to having a separate compiler.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>