Track finalizable objects in loops

`PrepareLoopStoredBy` is now aware of the finalizable attribute
and will crate a Phi rather than returning `PureUnknown`

Test: art/test/testrunner/testrunner.py --host --64 --optimizing -b
Change-Id: I203af6f7a9f5b02ede18ee038cabee67c667e5d0
2 files changed