Add support for fFormatArgs in .fp-file inner functions.

Previously, we'd just emit functions with `%s` in their function bodies.
Also, the fFormatArgs wouldn't get cleaned up, so subsequent code would
fill in the wrong format arguments in each place.

There are still problems with function calls (`sample` is broken;
function names are accessed before they've been declared or initialized)
but this is a step in the right direction.

Bug: skia:10684
Change-Id: I7399a71d44ebba5049703484ec9933dffbe8e2b9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/329417
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
4 files changed