[analyzer] Add a test for "release and stop tracking" behavior.

This is used to handle functions and methods that consume an argument
(annotated with the ns_consumed or cf_consumed attribute), but then the
argument's retain count may be further modified in a callback. We want
to warn about over-releasing, but we can't really track the object afterwards.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162221 91177308-0d34-0410-b5e6-96231b3b80d8