Update LLVM for 3.5 rebase (r209712).

Change-Id: I149556c940fb7dc92d075273c87ff584f400941f
diff --git a/lib/Support/GraphWriter.cpp b/lib/Support/GraphWriter.cpp
index 83aa255..f5b2943 100644
--- a/lib/Support/GraphWriter.cpp
+++ b/lib/Support/GraphWriter.cpp
@@ -83,7 +83,7 @@
 ExecGraphViewer(StringRef ExecPath, std::vector<const char*> &args,
                 StringRef Filename, bool wait, std::string &ErrMsg) {
   if (wait) {
-    if (sys::ExecuteAndWait(ExecPath, &args[0],0,0,0,0,&ErrMsg)) {
+    if (sys::ExecuteAndWait(ExecPath, &args[0],nullptr,nullptr,0,0,&ErrMsg)) {
       errs() << "Error: " << ErrMsg << "\n";
       return false;
     }
@@ -91,7 +91,7 @@
     errs() << " done. \n";
   }
   else {
-    sys::ExecuteNoWait(ExecPath, &args[0],0,0,0,&ErrMsg);
+    sys::ExecuteNoWait(ExecPath, &args[0],nullptr,nullptr,0,&ErrMsg);
     errs() << "Remember to erase graph file: " << Filename.str() << "\n";
   }
   return true;
@@ -108,7 +108,7 @@
   std::vector<const char*> args;
   args.push_back(Graphviz.c_str());
   args.push_back(Filename.c_str());
-  args.push_back(0);
+  args.push_back(nullptr);
 
   errs() << "Running 'Graphviz' program... ";
   if (!ExecGraphViewer(Graphviz, args, Filename, wait, ErrMsg))