Don't blat /var/run and /var/spool/lock *after* network_pass1()
unless /var is nfs-mounted.
This was removing ppps device lock (when ppp's started in
/etc/start_if.tun0 in -ddial or -dedicated mode) and allowing
other programs (such as mgetty) to confuse ppp by playing with
the modem while ppp's using it.

People that nfs-mount /var had better not start ppp in this
way....