We've been using the original dirs since dhcpcd-9.1.
dhcpcd-7 defaults the database directory to `/var/db/dhcpcd` instead of
`/var/db` and now stores dhcpcd.duid and dhcpcd.secret in there instead of
in /etc.
-dhcpcd-9 requires this directory and contents to be writeable by the
-unprivileged user (default _dhcpcd, _dhcp or dhcpcd).
-
-Of course this won't work if dhcpcd is packaged up, so packagers will need to
-install similar logic into their dhcpcd package.
dhcpcd-9 defaults the run directory to `/var/run/dhcpcd` instead of
`/var/run` and the prefix of dhcpcd has been removed from the files.