scheduling an interrupt thread to run when needed. This has the side
effect of enabling support for entropy gathering from interrupts on
all architectures.
- Change the software interrupt and x86 and alpha hardware interrupt code
to use ithread_schedule() for most of their processing when scheduling
an interrupt to run.
- Remove the pesky Warning message about interrupt threads having entropy
enabled. I'm not sure why I put that in there in the first place.
- Add more error checking for parameters and change some cases that
returned EINVAL to panic on failure instead via KASSERT().
- Instead of doing a documented evil hack of setting the P_NOLOAD flag
on every interrupt thread whose pri was SWI_CLOCK, set the flag
explicity for clk_ithd's proc during start_softintr().