Thread safety analysis: add array operations to SExpr.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206907 91177308-0d34-0410-b5e6-96231b3b80d8
Fix PR19487, PR19505 and PR19506 -- redundant vtordisp thunks when the final overrider is present in both a vbase and nvbase

Reviewed at http://reviews.llvm.org/D3449

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206908 91177308-0d34-0410-b5e6-96231b3b80d8