[Support] Merge toLower / toUpper implementations

Merge the ones from StringRef and StringExtras.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319171 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/StringExtras.cpp

@@ -13,6 +13,7 @@
 
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/raw_ostream.h"
 using namespace llvm;
 
 /// StrInStrNoCase - Portable version of strcasestr.  Locates the first
@@ -56,3 +57,8 @@ void llvm::SplitString(StringRef Source,
     S = getToken(S.second, Delimiters);
   }
 }
+
+void llvm::printLowerCase(StringRef String, raw_ostream &Out) {
+  for (const char C : String)
+    Out << toLower(C);
+}