Function gio_sys::g_async_initable_init_async

pub unsafe extern fn g_async_initable_init_async(initable: *mut GAsyncInitable,
                                                 io_priority: c_int,
                                                 cancellable: *mut GCancellable,
                                                 callback: GAsyncReadyCallback,
                                                 user_data: gpointer)