bug#37689: Fringe pixmaps, widgets, etc. look ridiculously tiny in hidpi screen

[Eli Zaretskii]

> From: Carlos Pita <carlosjosepita@gmail.com>
> Date: Fri, 11 Oct 2019 21:51:02 -0300
> Cc: Robert Pluim <rpluim@gmail.com>, 37689@debbugs.gnu.org
> 
> If you agree I might try implementing something like what my advice
> above does, but inside get_fringe_bitmap_data, with caching and
> generalizing it to more scaling factors; nevertheless, I would be
> keeping the integer scaling simplification since fractional scaling,
> specially for such tiny bitmaps, would require a lot of handcrafting.

Fine with me, thanks.