Update Clang for 3.5 rebase (r209713).

Change-Id: I8c9133b0f8f776dc915f270b60f94962e771bc83
diff --git a/lib/Analysis/PostOrderCFGView.cpp b/lib/Analysis/PostOrderCFGView.cpp
index cfd66f7..5a3c8182 100644
--- a/lib/Analysis/PostOrderCFGView.cpp
+++ b/lib/Analysis/PostOrderCFGView.cpp
@@ -31,7 +31,7 @@
 PostOrderCFGView *PostOrderCFGView::create(AnalysisDeclContext &ctx) {
   const CFG *cfg = ctx.getCFG();
   if (!cfg)
-    return 0;
+    return nullptr;
   return new PostOrderCFGView(cfg);
 }