take advantage of the rc.subr(8) glue. They are renamed dhclient_program
and dhclient_flags.
o Rename them in rc.conf(5)
o Rename them in /etc/defaults/rc.conf
o Add the deprecated variables to /etc/rc.subr
o Isolate the use of the 'command' variable to the
NetBSD specific parts in /etc/rc.d/dhclient.
o Now that dhcp_flags has also been renamed it will
be applied properly by rc.subr(8) glue code.
Reported by: John Nielsen <john@jnielsen.net>