SkMD5 returns digest

Change-Id: I9eb9095131adb5862d286b211501bf194ef8e91e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/205822
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>
10 files changed