ObjectiveC. Fixes a bogus warning of unused backing
ivar when property belongs to a super class and
currnt class happens to have a method with same name as
property. // rdar//15473432


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@194830 91177308-0d34-0410-b5e6-96231b3b80d8