bug#20802: Segfault when showing non-GTK+ tooltip

[Eli Zaretskii]

> Date: Thu, 18 Jun 2015 19:36:07 +0200
> From: martin rudalics <rudalics@gmx.at>
> CC: tobias.getzner@gmx.de, 20802@debbugs.gnu.org
> 
>  > but please keep in mind that we never delete a terminal
>  > on Windows, until Emacs exits.
> 
> So on Windows we would keep the image cache forever?

Yes.  We keep it forever already.  Well, except maybe with the
recently-added daemon mode, when all the frames are gone.