Function gio_sys::g_file_enumerator_next_files_async

pub unsafe extern fn g_file_enumerator_next_files_async(enumerator: *mut GFileEnumerator,
                                                        num_files: c_int,
                                                        io_priority: c_int,
                                                        cancellable: *mut GCancellable,
                                                        callback: GAsyncReadyCallback,
                                                        user_data: gpointer)