Revert r245802. It violates the incomplete type requirements.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@245805 91177308-0d34-0410-b5e6-96231b3b80d8

include/memory

@@ -932,15 +932,6 @@ public:
         {return _VSTD::addressof(__r);}
 };
 
-template <class _From, class _To>
-struct __rebind_pointer {
-#ifndef _LIBCPP_HAS_NO_TEMPLATE_ALIASES
-    typedef typename pointer_traits<_From>::template rebind<_To>        type;
-#else
-    typedef typename pointer_traits<_From>::template rebind<_To>::other type;
-#endif
-};
-
 // allocator_traits
 
 namespace __has_pointer_type_imp