Introduce SkAutoMutexExclusive for SkMutex RAII.
Unsubclass SkMutex from SkBaseMutex to allow annotations
for class field mutexes separate from global mutexes.
Leave SkAutoMutexAcquire for handling global mutexes using
SkBaseMutex.
Test using GrSingleOwner.h.
Change-Id: I19d9d0ae0d05206cbb6ef137dc362969048c9c07
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/213136
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
9b86955c65