With the addition of a profile hook for computing the gdk-pixbuf loaders cache
file, there is no longer a need for gdk-pixbuf+svg, and librsvg can propagate
gdk-pixbuf without fear, so replace the former for the latter.
The replacement was automated with the following command:
$ git grep -l ',gdk-pixbuf+svg)' \
| xargs sed 's/(".*" ,gdk-pixbuf+svg)/("librsvg" ,librsvg)/' -i
* gnu/packages/gtk.scm (gdk-pixbuf+svg): Delete package.
(gtk+-2)[propagated-inputs]: Replace gdk-pixbuf+svg with librsvg.
(gtk+)[propagated-inputs]: Likewise.
* gnu/packages/gnome.scm (gdk-pixbuf+svg): Add deprecated package.
* gnu/packages/dunst.scm (dunst): Update to 1.2.0.
[inputs]: Update: remove 'libxext' and 'libxft', add 'gtk' and 'libxrandr'.
[home-page]: Update for the new location.
