r233961:
Fix interrupt load balancing regression, introduced in revision
222813, that left all un-pinned interrupts assigned to CPU 0.
In intr_shuffle_irqs(), remove CPU_SETOF() call that initialized
the "intr_cpus" cpuset to only contain CPU0.
This initialization is too late and nullifies the results of calls
to the intr_add_cpu() that occur much earlier in the boot process.
r234074 (partial):
The BSP is not added to the mask of valid target CPUs for interrupts.
Fix this by adding the BSP as an interrupt target directly in
r234105:
Fix !SMP build after r234074.
MFC after: 3 days
7b88f42369