bug#47074: Replace XPM icons with Unicode codepoints in customize/widgets

[Eli Zaretskii]

> Date: Sat, 3 Apr 2021 23:28:35 +0100
> From: Alan Third <alan@idiocy.org>
> Cc: Eli Zaretskii <eliz@gnu.org>, 47074-done@debbugs.gnu.org
> 
> I've pushed a change up, so hopefully it should all Just Work now.

Alan, this patch calls malloc to allocate face_font_family, but then
calls xfree to free it.  Why didn't you call xmalloc to allocate?
that's currently the only caller of malloc in the entire image.c.