THIRD TIME. Richard pointed out (again) that I'd switched the order of the instance variables; and thus failed to repair the ABI break. After this, I'm going to sit down and watch TV for the evening.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@203631 91177308-0d34-0410-b5e6-96231b3b80d8