Update component arrays to use SkSTArray<4, int8_t>.

Profiling sksl_large showed a non-trivial amount of time was spent on
allocating vector<int>s related to swizzle components. This CL
essentially eliminates that cost, for a ~2% savings.

Nanobench before: http://screen/35m2rfy5B8h9eyg
Nanobench after:  http://screen/4GuW6ipodyBL34h

Change-Id: I653b69bf1bfbcfdf048987edd23e6f14a5ef3fbc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/330336
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
6 files changed