Add fields to fragmentProcessors in sksl code.

Getters for GrFragmentProcessor's optimization flags and state are
exposed as constant fields on the fragmentProcessor variable in sksl.
The CPP code generation then emits extra instructions to invoke the
particular getter when building the final sksl string at runtime.

Bug: skia:
Change-Id: If6bf4f4df6c446fb6331484d36effb1386172918
Reviewed-on: https://skia-review.googlesource.com/152381
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
8 files changed