Add compile-time optimization for transpose().

Change-Id: I9ddb80b8886827250e243dc9174bb3679e70df9b
Bug: skia:12202
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/440262
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
5 files changed