Remove unnecessary uses of <iostream>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101338 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/opt/GraphPrinters.cpp b/tools/opt/GraphPrinters.cpp
index bbf8d12..86f9932 100644
--- a/tools/opt/GraphPrinters.cpp
+++ b/tools/opt/GraphPrinters.cpp
@@ -19,12 +19,11 @@
 #include "llvm/Value.h"
 #include "llvm/Analysis/CallGraph.h"
 #include "llvm/Analysis/Dominators.h"
-#include <iostream>
-#include <fstream>
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 template<typename GraphType>
-static void WriteGraphToFile(std::ostream &O, const std::string &GraphName,
+static void WriteGraphToFile(raw_ostream &O, const std::string &GraphName,
                              const GraphType &GT) {
   std::string Filename = GraphName + ".dot";
   O << "Writing '" << Filename << "'...";
@@ -69,7 +68,7 @@
     CallGraphPrinter() : ModulePass(&ID) {}
 
     virtual bool runOnModule(Module &M) {
-      WriteGraphToFile(std::cerr, "callgraph", &getAnalysis<CallGraph>());
+      WriteGraphToFile(llvm::errs(), "callgraph", &getAnalysis<CallGraph>());
       return false;
     }