Increase GetLoopUnrollInfo loop-count limit to 100,000.

To do this with a clean conscience, I needed to convert the unroll-
counting logic from a linear time algorithm to constant-time. Getting
all the edge cases correct requires a lot of care, and there are now
plenty of unit tests.

Change-Id: I620909d069ac425b7310e345bf80ec844fe035f8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/445643
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
3 files changed