build: add entt library

include/entt/stl/utility.hpp

@@ -0,0 +1,34 @@
+#ifndef ENTT_STL_UTILITY_HPP
+#define ENTT_STL_UTILITY_HPP
+
+/*! @cond ENTT_INTERNAL */
+#if __has_include(<entt/ext/stl/utility.hpp>)
+#    include <entt/ext/stl/utility.hpp>
+#else
+#    include <utility>
+
+namespace entt::stl {
+
+using std::as_const;
+using std::declval;
+using std::exchange;
+using std::forward;
+using std::in_place;
+using std::in_place_t;
+using std::in_place_type;
+using std::in_place_type_t;
+using std::index_sequence;
+using std::index_sequence_for;
+using std::make_index_sequence;
+using std::make_pair;
+using std::move;
+using std::pair;
+using std::piecewise_construct;
+using std::piecewise_construct_t;
+using std::swap;
+
+} // namespace entt::stl
+#endif
+/*! @endcond */
+
+#endif