ObjectiveC migration. Check-in patch reverted in r187634.
Also removed check for "NS" prefix for class name.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187655 91177308-0d34-0410-b5e6-96231b3b80d8
revert patch I added in r187655. It still breaks public
buildbot.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@187657 91177308-0d34-0410-b5e6-96231b3b80d8