[PM] Stop playing fast and loose with rebinding of references. However
convenient it is to imagine a world where this works, that is not C++ as
was pointed out in review. The standard even goes to some lengths to
preclude any attempt at this, for better or worse. Maybe better. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203775 91177308-0d34-0410-b5e6-96231b3b80d8