is NOT disarmed when wdogctl closes the watchdog device. The -x
mode protects against the case where the kernel kills wdogctl,
sshd, and other essential userland programs (due to memory exhaustion,
for example), lobotomizing a mission-critical NetBSD system and
necessitating an operator visit to reboot it.
killing self, instead of the other way around.
Fixes a bug where the child process would use 100% CPU spinning
while it waited for its parent to arm a non-existent watchdog timer.
Now, the child process gets killed, as was intended.
changes the "tickle" model of wdogctl(8), it was modified as well;
while I was in there, I cleaned up the argument parsing.
The code was reviewed by simonb@.
