I just noticed on the core-updates-frozen branch that there are libxml++
packages (in gnome.scm) and also libxmlplusplus packages (in xml.scm).
I checked the sources of libxml++-2.40.1 and libxmlplusplus-2.40.1, and
it looks like it is the same library.

I think we could keep only the libxmlplusplus ones and remove the others.
Does someone have an objection?