Give device names to ithreads p_comm and evcounters to softintr.

Concatenate all device names in the ithread's process name, this is
useful for debugging and/or profiling.

Also put event counters on software interrupts, I can't recall how
many times I wanted to know this.

A ps auxkl might show the following now:

root      6034  0.0  0.0      0      0 ??  DK     2:01AM    0:04.97 (softclock)          0     0   0 -18   0 intr
root     24717  0.0  0.0      0      0 ??  DK     2:01AM    0:01.06 (softnet)            0     0   0 -18   0 intr
root     25481  0.0  0.0      0      0 ??  DK     2:01AM    0:01.08 (ehci0,mpi0)         0     0   0 -18   0 intr
root     23688  0.0  0.0      0      0 ??  DK     2:01AM    0:01.02 (em0)                0     0   0 -18   0 intr
....