bug#58028: 29.0.50; Ensures no leakage of glyph_matrix

[Eli Zaretskii]

> From: Manuel Giraud <manuel@ledu-giraud.fr>
> Cc: 58028@debbugs.gnu.org
> Date: Fri, 23 Sep 2022 17:59:48 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> From: Manuel Giraud <manuel@ledu-giraud.fr>
> >> Date: Fri, 23 Sep 2022 17:22:07 +0200
> >> 
> >> Maybe this problem never triggers.  It is a « better be safe » kind of
> >> patch.
> >
> > Please add an assertion there, to catch the case that previously was
> > handled by testing only w->desired_matrix.
> 
> I do not understand what you mean here.

I mean the assertion that triggers when w->desired_matrix is NULL, but
w->current_matrix isn't.