send pmap tlb shootdowns to them cause the shootdown job queue to fill up,
but since the cpus aren't running yet, no IPIs get sent. When the job
queue is full, the bit mask of cpus to send the IPI to is not set and no
shootdown IPI ever gets sent after the cpu is marked running. Always
set the cpumask even when the queue is full. Now I get shootdown ipis
on all the secondary cpus.