LOG_CRIT+ messages should be reported to root via alert system

[gcooper]

I'd have to doublecheck whether or not samba uses the right severity, but in general any items that are a certain syslog(3) log priority should be passed along to root, so critical items can be tracked (say, disk failure? mps channel droppage? etc) and there will be a proper audit log to help articulate that there's a problem that needs resolving on the host system.

This is a touchy item as it can result in more support emails than necessary, so extensive testing with various failure conditions and soak testing will need to be applied. I do not recommend this for FreeNAS 8.2.0, but instead 8.3.0.