CachedHashString.h - remove unnecessary includes. NFC.

We don't need the full DenseMap.h just DenseMapInfo.h

Author: RKSimon

llvm/include/llvm/ADT/CachedHashString.h

@@ -19,9 +19,8 @@
 #ifndef LLVM_ADT_CACHED_HASH_STRING_H
 #define LLVM_ADT_CACHED_HASH_STRING_H
 
-#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseMapInfo.h"
 #include "llvm/ADT/StringRef.h"
-#include "llvm/Support/raw_ostream.h"
 
 namespace llvm {