SFINAE corrected as specified in P0052.

include/unique_resource.h

         }
 
         template<class RR = R,
-                std::enable_if_t<std::is_pointer<RR>::value && std::is_nothrow_copy_constructible<RR>::value
+                std::enable_if_t<std::is_pointer<RR>::value
                                 && ( std::is_class<std::remove_pointer_t<RR>>::value
-                                        || std::is_union<std::remove_pointer_t<RR>>::value ), int> = 0
+                                    || std::is_union<std::remove_pointer_t<RR>>::value ), int> = 0
                 >
         RR operator->() const noexcept
         {