prune the #includes in raw_ostream.h by moving a 
member out of line. ftostr is not particularly speedy,
so that method is presumably not perf sensitive.

llvm-svn: 79885
diff --git a/llvm/lib/Target/CppBackend/CPPBackend.cpp b/llvm/lib/Target/CppBackend/CPPBackend.cpp
index 3de81a4..bebad66 100644
--- a/llvm/lib/Target/CppBackend/CPPBackend.cpp
+++ b/llvm/lib/Target/CppBackend/CPPBackend.cpp
@@ -28,6 +28,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Target/TargetRegistry.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Config/config.h"
 #include <algorithm>
 #include <set>