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

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sun, 14 Mar 2021 13:44:32 -0500
> Cc: Eli Zaretskii <eliz@gnu.org>, 47074@debbugs.gnu.org
> 
> This is exactly the behavior I was thinking of, yes.  It looks and works
> great in some minor testing.
> 
> Maybe Lars or Eli have additional comments, but LGTM.

The only question I have is what will happen if librsvg is older than
2.48?