This was part of the gnome2 package set, which is being removed. This is
likely to be removed soon as well for depending on GTK2, but for now we
can move it to by-name at the top level.
Fixes issues with the help browser by copying vocabulary roots instead
of symlinking them. Although, I am convinced that this is an issue that
should be fixed upstream, eventually.
Fixes#469242Fixes#474869
