roll clang to 9.0

Change-Id: Idd54caf1a9688a5de2fba08e8ae834f209aefc1c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/242879
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
3 files changed