Don't lifetime-extend or track lifetime problems through the LHS of '->*'.

Fixes a false-positive warning found by selfhost.

llvm-svn: 337857
diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index 3d11619..7e652b7 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -108,7 +108,7 @@
         }
       }
     } else if (const BinaryOperator *BO = dyn_cast<BinaryOperator>(E)) {
-      if (BO->isPtrMemOp()) {
+      if (BO->getOpcode() == BO_PtrMemD) {
         assert(BO->getRHS()->isRValue());
         E = BO->getLHS();
         const MemberPointerType *MPT =