All existing DHCPv4 packages I looked at were unappealing for one reason or
another, so we’re now using a little helper to glue github.com/google/gopacket
and github.com/mdlayher/raw together, which suffices for our use-case and gives
us more control.
We can do away with a bunch of hacks now, but we’ll keep them around for a
little while to make updates easier (i.e. to boot with old and new gokr-packer
versions, just in case people don’t update both at the same time).
E.g. /etc/kresd/dhcp_host_domain_ng.sh on a turris omnia incorrectly deletes
DHCP hostname mappings when more than one client does not send a client id.
