Objective-C IRGen. Fix up the hueristics for determining
if an ivar offset load is invariant iff inside an instance method
and ivar belongs to instance method's class and one of its super class.
// rdar://16095748


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@202872 91177308-0d34-0410-b5e6-96231b3b80d8