Log Message:
Updated qpopper to 4.0.4

* Fixed DOS attack seen on some systems.
* Fixed "noop has null function" log entry.
* Allow '-p' to be used when APOP not defined (noted by Daniel Senie).
* Enforce ClearTextPassword even without APOP (noted by Daniel Senie).
* Restrict clear-text-password=never to APOP.
* Restrict clear-text-password=tls to QPOP_SSL.
* Fixed qpopper hanging on I/O error on some platforms.