bug#20890: master 1233bcb: Work around GC+Cairo bug

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: 20890@debbugs.gnu.org,  eggert@cs.ucla.edu
> Date: Wed, 04 Apr 2018 14:10:12 +0200
> 
> > If you can tell why FT_List_Find crashes, in terms of Emacs variables
> > and data structures, maybe we can figure out what is going on here.
> > But in any case, I think we should put the same workaround in
> > ftcrfont_close as we did in ftfont_close, because the former calls the
> > latter, and we then risk the situation where we only half-close the
> > font when ftcrfont_close is called from GC.
> 
> That same workaround fixes it on Ubuntu.

Then I think we should install it.