Restore lua 5.2/5.3 compatibility (fixes #1408)

src/common/runtime.cpp

@@ -879,4 +879,13 @@ Type *luax_type(lua_State *L, int idx)
 	return Type::byName(luaL_checkstring(L, idx));
 }
 
+int luax_resume(lua_State *L, int nargs)
+{
+#if LUA_VERSION_NUM >= 502
+	return lua_resume(L, nullptr, nargs);
+#else
+	return lua_resume(L, nargs);
+#endif
+}
+
 } // love