bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1'

[Eli Zaretskii]

> From: Alexander Shukaev <emacs@Alexander.Shukaev.name>
> Date: Thu, 3 Sep 2020 21:47:41 +0200
> Cc: 43177@debbugs.gnu.org
> 
> >> So the solution is easy: just deprecate and remove the 'x' backend :-)
> >>
> >> Robert
> >>
> > 
> > Love that tip, man!  Confirming the speed up.  Thanks a lot!
> 
> For future visitors and for completeness sake, my per-frame font setup 
> function now looks like this:

For those same future visitors, a word of warning: removing the x font
backend will make some (rarely used) fonts unavailable to Emacs.
Caveat emptor!