Both qemu-system-common and our pve-qemu-kvm package install the
file /usr/bin/virtfs-proxy-helper.
Since qemu-system-common does not have reverse dependencies in Debian for
packages besides qemu-system-<arch>, and ovmf, which we don't want to
install anyway, we do not need a 'Provides' for it.
Acked-by: Wolfgang Bumiller <w.bumiller@proxmox.com>