Use SkSTArray to track CFG exits instead of std<set>.

This improves SkSL compile times by about 1-2%.
Nanobench: http://screen/BL5kKgwzEzTNqSu

Change-Id: I85df42bdd33cfce13345f11d588283eeaf5643d0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/324061
Commit-Queue: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
2 files changed