Log Message:
Fix some long-standing kqueue bugs that have been bothering me for a long
time.  For example, simply running 'nautilus /' could lock up famd in pipewr
status.  To fix:

- Make the struct devino's sorting function work properly; otherwise the
  map behaves incorrectly.
- Handle kqueue errors if they are returned as an entry in the events table
  (with flags containing EV_ERROR).

While here, add more debugging code that helped me catch this issue (some
extra messages and assertions).

Also reenable assertions (except on Darwin as, according to version 1.14 of
the Makefile, they cause problems).

Not bumping revision because kqueue support is still off by default.