Use GEPs correctly when adjusting this in MicrosoftCXXABI

Reviewed at http://llvm-reviews.chandlerc.com/D1977

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@193176 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed