bug#57522: 29.0.50; Fix submenu indicator on X11 no toolkit

[Eli Zaretskii]

> Cc: 57522@debbugs.gnu.org
> Date: Fri, 02 Sep 2022 16:25:34 +0800
> From:  Po Lu via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Manuel Giraud <manuel@ledu-giraud.fr> writes:
> 
> > Ok but then there is no visual indication whether a menu entry leads to
> > a submenu pane or an action.
> 
> I guess there isn't, but that info should be fairly obvious from the
> entry name, right?

No, it isn't.  Or at least it doesn't have to be.  Which is why the
">" part is important.  It emulates what toolkit menus do when a menu
item has sub-menus.