'd': now means don't do daemon().
'D': Debug
'n': Don't wait to process all pending events before calling daemon.
In the past, devd would call daemon immediately. However, this causes
a race. If anything in the boot process depends on configuring the
devices configured by devd, maybe they would be configured in time,
maybe not. Now we don't call daemon until all pending events are
processed, unless -n is specified.
# -n is actually the default for a while due to the select(2) bug in devctl
# that I just fixed to give people a chance to upgrade.
5a882d775d