Function gio_sys::g_file_copy

pub unsafe extern fn g_file_copy(source: *mut GFile,
                                 destination: *mut GFile,
                                 flags: GFileCopyFlags,
                                 cancellable: *mut GCancellable,
                                 progress_callback: GFileProgressCallback,
                                 progress_callback_data: gpointer,
                                 error: *mut *mut GError)
                                 -> gboolean