[ptr-traits] Add one more #include necessary to do strict alignment

checking of pointers used in PointerIntPairs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@256617 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/Mangler.h

@@ -15,12 +15,12 @@
 #define LLVM_IR_MANGLER_H
 
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/IR/GlobalValue.h"
 #include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
 
 class DataLayout;
-class GlobalValue;
 template <typename T> class SmallVectorImpl;
 class Twine;