This libs are required by both dom0 and VM so it's better to have it
separately. Previously in VM it was separate package, but dom0 have them
embedded in qubes-core-dom0, but qubes-core-vm-libs package was used to build
qubes-gui-dom0. Now we do not build all packages for all distros (especially do
not build core-vm package for dom0 distro, so gui-dom0 build fails), so make it
explicit which package is needed by which system.
