bug#32672: 27.0.50; image resize on window resizing

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: 32672@debbugs.gnu.org
> Date: Thu, 27 Dec 2018 22:58:04 +0200
> 
> >> +          (when (or (not (= image-width  window-width))
> >> +                    (not (= image-height window-height)))
> >> +            (image-toggle-display-image)))))))
> >
> > What happens in Emacs that was not built with Imagemagick?  Should we
> > perhaps do nothing in this hook in that case?
> 
> Let's hope that native image scaling will handle this properly.

We don't have that yet, so we should do something about that in the
meantime.