Objective-C [qoi]. When reporting that a property is not
auto synthesized because it is synthesized in its super
class. locate property declaration in super class
which will default synthesize the property. rdar://18488727


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@219535 91177308-0d34-0410-b5e6-96231b3b80d8