Update LLVM for 3.5 rebase (r209712).

Change-Id: I149556c940fb7dc92d075273c87ff584f400941f
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
index 5e11dbb..39ebadf 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.h
@@ -139,7 +139,7 @@
     public:
       RegDefIter(const SUnit *SU, const ScheduleDAGSDNodes *SD);
 
-      bool IsValid() const { return Node != NULL; }
+      bool IsValid() const { return Node != nullptr; }
 
       MVT GetValue() const {
         assert(IsValid() && "bad iterator");