[patch] zfs livelock and thread priorities

[Ryan Stone]

The crash happens because vsnprintf is called twice on the same va_list.
That's not legal.  It happens to work on i386, but it will crash on amd64.
The patch should instead do:

va_list va;
va_start(ap, fmt);
va_copy(va, ap);
vsnprintf(p2->p_comm, sizeof(p2->p_comm), fmt, va);
vsnprintf(td->td_name, sizeof(td->td_name), fmt, ap);

Ryan Stone