Revert r185852.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185861 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/StringRef.cpp

@@ -11,7 +11,6 @@
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/OwningPtr.h"
-#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/edit_distance.h"
 #include <bitset>
 
@@ -466,7 +465,3 @@ bool StringRef::getAsInteger(unsigned Radix, APInt &Result) const {
 hash_code llvm::hash_value(StringRef S) {
   return hash_combine_range(S.begin(), S.end());
 }
-
-unsigned DenseMapInfo<StringRef>::getHashValue(StringRef const val) {
-  return llvm::HashString(val);
-}