ObjectiveC migrator: tighten the rules for when
inferring NS_RETURNS_RETAINED, etc., return annotations.
Do not infer if these annotations are implicit
from the naming convention. Also add inference for
NS_CONSUMES_SELF annotation.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@190106 91177308-0d34-0410-b5e6-96231b3b80d8