Reproducable panic in in6_pcbbind

[Craig Boston]

> I experienced the same kgdb trace last manth. I found the crashdump
> lied about where the trap occured. What DDB prints? If the true trap
> point is at in6_pcbbind() in netinet6/in6_pcb.c, the problem may be
> same to kern/50621.

This may be the same problem.  It happens if I disconnect and quickly
reconnect the ssh session (causing ssh to open a listener socket on
::1).  I thought it might be related to TIME_WAIT, and kern/50621 seems
to point to that as well.

I do have a serial console hooked up, so as soon as I get a moment when
I can remount everything read-only I'll try to trigger the bug and see
what DDB says.

Craig