Switch many jobs to Clang.

No-Try: true
Change-Id: Ie255d46ff50d13d25d045791c1c3066f06ab9243
Reviewed-on: https://skia-review.googlesource.com/53601
Commit-Queue: Ben Wagner <benjaminwagner@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
16 files changed