Revert r170806, "Fix some bugs where we would sometimes use 0, not -1, when emitting a null constant of type pointer-to-data-member."

It broke stage2.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@170835 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed