Stop linking libflatpak against listappstream-glib
Stop linking libflatpak against listappstream-glib

We no longer use it here. flatpak itself still links
against it. This avoids problems with consumers who
might also link against libappstream.

Closes: #2580
Approved by: alexlarsson

flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak