Update Clang for 3.5 rebase (r209713).

Change-Id: I8c9133b0f8f776dc915f270b60f94962e771bc83
diff --git a/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp b/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp
index dc53602..cc4c0c3 100644
--- a/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp
+++ b/lib/StaticAnalyzer/Checkers/CheckObjCInstMethSignature.cpp
@@ -106,12 +106,12 @@
 
       MapTy::iterator MI = IMeths.find(S);
 
-      if (MI == IMeths.end() || MI->second == 0)
+      if (MI == IMeths.end() || MI->second == nullptr)
         continue;
 
       --NumMethods;
       ObjCMethodDecl *MethDerived = MI->second;
-      MI->second = 0;
+      MI->second = nullptr;
 
       CompareReturnTypes(MethDerived, M, BR, Ctx, ID, Checker);
     }