Fixed #6938: Remote app mode clipboard fix

In remote app mode the _FREERDP_TIMESTAMP_PROPERTY does not work.
Therefore ignore it

(cherry picked from commit f2254f0b09a5fbc424ef3876cb47b03d83963c38)

client/X11/xf_cliprdr.c

@@ -1423,7 +1423,10 @@ static UINT xf_cliprdr_server_format_list(CliprdrClientContext* context,
 	}
 
 	ret = xf_cliprdr_send_client_format_list_response(clipboard, TRUE);
-	xf_cliprdr_prepare_to_set_selection_owner(xfc, clipboard);
+	if (xfc->remote_app)
+		xf_cliprdr_set_selection_owner(xfc, clipboard, CurrentTime);
+	else
+		xf_cliprdr_prepare_to_set_selection_owner(xfc, clipboard);
 	return ret;
 }