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/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index 895a87b..75843e8 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -47,6 +47,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
 #include <set>
 using namespace llvm;