Another RPI3 panic: Assertion td->td_lock == TDQ_LOCKPTR(tdq)

[bob prohaska]

For the second time during an OS build attempt a Pi3 running r328436 has
crashed with 

panic: Assertion td->td_lock == TDQ_LOCKPTR(tdq) failed at /usr/src/sys/kern/sched_ule.c:2019

Console, top and build logs are at
http://www.zefox.net/~fbsd/rpi3/crashes/20180128/

The log files are from kernel building. Unfortunately I didn't
capture the world build console and log. 

Thanks for reading, 

bob prohaska