Summary:
The way interfaces are dealt with led to a false positive,
where tryLock() works OK for a Lock but not for a ReentrantLock.
The solution is just to provide the model.
While I am at it I am adding some more standard tests for Lock and ReentrantLock, which were not present.
Reviewed By: sblackshear
Differential Revision: D4204551
fbshipit-source-id: 9b6de28