[Dovecot] BSD kqueue testing, once more before 1.0rc7

I did a few more changes and it seems to be working with FreeBSD. I didn't before realize that event filters weren't bitmasks so that broke things.

Anyway, a bit more "real world testing" would be better than my test program and telnet localhost -tests :)

I'll release 1.0rc7 in any case today before I go to sleep (so, max. 6 hours or so).

http://dovecot.org/nightly/dovecot-latest.tar.gz