Allow an onrestart command to stop the current service

For example,

service recovery /sbin/recovery
	onrestart start loadkeys
	onrestart class_start con
	onrestart stop recovery

Previously, if you had a service like the above, the "onrestart stop
recovery" clause would not have any effect, because the restart flag
would be re-set after the stop command had executed.

This is similar to a service with the "oneshot" keyword, with the critical
difference being that it executes the other onrestart commands when the
service dies.