Log Message:
Update Cyrus IMAPd to 2.3.11.
While here, DESTDIR ready.

Noteworthy changes:
 
      * Fixed several skiplist bugs -- courtesy of Fastmail.fm.
      * Add robustness to skiplist recovery -- courtesy of Fastmail.fm.
      * Added support for modification sequences to replication protocol
        (for CONDSTORE) -- courtesy of David Carter.
      * Fixed delayed delete replication -- courtesy of Fastmail.fm.
      * Allow [un]deleting of user INBOXes (renaming to/from deleted
        hierarchy) to work when using delayed delete -- courtesy of Simon
        Matter.
      * Prevented SSL_accept() from blocking indefinitely when using
        TLS/SSL.