Speculatively fixing the build; it seems add_pointer_t and add_const_t are not implemented everywhere.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348731 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/ADT/STLExtras.h b/include/llvm/ADT/STLExtras.h
index 789b09f..8685f0e 100644
--- a/include/llvm/ADT/STLExtras.h
+++ b/include/llvm/ADT/STLExtras.h
@@ -72,7 +72,8 @@
     : std::conditional<bool(B1::value), conjunction<Bn...>, B1>::type {};
 
 template <typename T> struct make_const_ptr {
-  using type = std::add_pointer_t<std::add_const_t<T>>;
+  using type =
+      typename std::add_pointer<typename std::add_const<T>::type>::type;
 };
 //===----------------------------------------------------------------------===//
 //     Extra additions to <functional>