[Dovecot] Linux SO_REUSEPORT

I just read about Linux v3.9's SO_REUSEPORT feature and decided to implement it for Dovecot. Would be interesting to know how it works for people :) It's going to be in v2.2.6, which I'm planning on releasing tomorrow. Note especially the warning about the bug:

http://hg.dovecot.org/dovecot-2.2/rev/a991a0547daa

So the idea is that you'd do something like:

service imap-login { inet_listener imap { reuse_port = yes } process_min_avail = 4 # number of CPU cores }

And the load should be distributed more evenly to the processes.