ibus: SetCursorLocationRelative is not a caret

A GTK client on the Wayland backend sends this where an X11 one sends
SetCursorLocation, and ictab did not list it, so libdbus answered
UnknownMethod.  Accept it and throw it away: the absolute translation
sits inside GDK_IS_X11_DISPLAY, so the coordinates are surface local,
and ibus's own daemon will not hand them to an engine either.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/ibus_live_test.c

@@ -128,6 +128,7 @@ runcontract(char *address)
 		"SetEngine",
 		"SetCapabilities",
 		"SetCursorLocation",
+		"SetCursorLocationRelative",
 	};
 	DBusConnection *conn;
 	char path[96];