Update dovecot2 to 2.2.20, and bump PORTREVISION on antispam-plugin and
pigeonhole.

Also, remove the GC option from dovecot2. As reported in bug #205035,
reported by sebastian@wolfgarten.com, all it does it cause leaks and
spam the logs about it.

Changes:
+ Added mailbox { autoexpunge=<time> } setting. See

http://wiki2.dovecot.org/MailboxSettings for details.

+ ssl_options: Added support for no_ticket
+ imap/pop3/managesieve-login: Added postlogin_socket=path passdb extra

field. This allows replacing the default service
imap/pop3/managesieve {} settings for specific users (e.g. running
their imap process via valgrind or strace).

+ doveadm fetch: Added date.sent/received/saved.unixtime
+ fs-posix: Added mode=auto parameter to set the created files' and

directories' mode based on the parent dir if it has setgid-bit.

+ director: Support backends having hostnames, which makes it possible

to verify their SSL certificates.

• director: Directors' state became desynchronized if doveadm director commands were used to modify the same backend in multiple directors at the same time with conflicting changes. This fix includes some extra checks, which makes sure that if such a conflict still happens it's automatically fixed. In some situations such an automatic fix may now be unnecessarily triggered and an error logged.
• director: Backend tags weren't working correctly.
• ldap: tls_* settings weren't used for ldaps URIs.
• ldap, mysql: Fixed setting connect timeout.
• auth: userdb lookups via auth-worker couldn't change username
• dsync: Fixed handling deleted directories. Make sure we don't go to infinite mailbox renaming loop.
• imap: Fixed crash in NOTIFY when there were watched namespaces that didn't support NOTIFY.
• imap: After SETMETADATA was used, various commands (especially FETCH) could have started hanging when their output was large.
• stats: Idle sessions weren't refreshed often enough, causing stats process to forget them and log errors about unknown sessions when they were updated later.
• stats: Fixed "Duplicate session ID" errors when LMTP delivered to multiple recipients and fts_autoindex=yes.
• zlib plugin: Fixed copying causing cache corruption when zlib_save wasn't set, but the source message was compressed.
• fts-solr: Fixed escaping Solr query parameters.
• lmtp: quota_full_tempfail=yes was ignored with lmtp_rcpt_check_quota=yes