Change already inline error to warning

There is a race condition in the JIT where the JIT and another
running thread can both verify the same method at the same time.
This causes the inline method to be added twice and the LOG(ERROR)
was causing occasional test failures.

Bug: 17950037
Bug: 18713034
Change-Id: I7f94384106ca5c621a5cf7d2ba36910d923d110c