Objective-C. Introducing __attribute__((objc_runtime_name("runtimename"))
to be applied to class or protocols. This will direct IRGen
for Objective-C metadata to use the new name in various places
where class and protocol names are needed.
rdar:// 17631257


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@213167 91177308-0d34-0410-b5e6-96231b3b80d8