Apply Jeffrey Yasskin's CallbackVH patch, with minor tweaks from me
to make the copy constructor and destructor protected, and corresponding
adjustments to the unittests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70644 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed