Prevent name collisions between variables and intrinsics.

If a variable is named after an intrinsic, we will now always
mangle it. I've also moved the mangling logic into Make, to avoid
performing this lookup every time `mangledName()` is called.

Our test case now generates valid code.

Bug: b/278599533
Change-Id: I501b0d2bbe4d511761bbe3acef5c9ac00f7b0c2a
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/693580
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
10 files changed