Explicitly #include Support/Streams.h when using llvm::cout and friends.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@51391 91177308-0d34-0410-b5e6-96231b3b80d8

Driver/RewriteObjC.cpp

@@ -23,6 +23,7 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Streams.h"
 #include "llvm/System/Path.h"
 #include <sstream>
 #include <fstream>