kernel - Test pending ints in more crit_exit*() paths

kernel - Test pending ints in more crit_exit*() paths

* A number of crit_exit*() paths, primarily in the mutex and
  spinlock code, were not testing for interrupts made pending
  on the last unwind of the critical section.

  This was originally intended to improve performance, but it
  can lead to non-deterministic latencies for processing interrupts.

* Process these pending events in such cases.  We will see if it
  affects performance but I don't think it will be noticeable.