Function gio_2_0_sys::g_file_enumerator_next_files_async

pub unsafe extern "C" fn g_file_enumerator_next_files_async(
    enumerator: *mut GFileEnumerator, 
    num_files: gint, 
    io_priority: gint, 
    cancellable: *mut GCancellable, 
    callback: Option<GAsyncReadyCallback>, 
    user_data: gpointer
)