Objective-C IRGen. Fixes an assertion crash caused by inconsistent
linkage related to generation of OBJC_SELECTOR_REFERENCES symbol 
needed in generation of call to 'super' in a class method.
// rdar://18150301


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@216676 91177308-0d34-0410-b5e6-96231b3b80d8