Log Message:
Update mimedefang to version 2.52

Changes in 2.52
* mimedefang.pl.in (item_contains_virus_fprotd): Remove all references
  to $` and $', which can SIGNIFICANTLY slow down Perl regexp matching.
* mimedefang.c(mfconnect): Do not call set_dsn from mfconnect, because
  the Milter API specifies that you can't call smfi_setreply from the
  connect callback.
* mimedefang-filter.5.in: Document the fact that filter_relay
  cannot set the text of the SMTP reply code.
* mimedefang.pl: We don't detect and load Perl modules until
  the detect_and_load_perl_modules() function is called.

  *** NOTE INCOMPATIBILITY ***

  You *MUST* call detect_and_load_perl_modules() inside your filter
  before you can rely on the %Features hash being set correctly,
  and before you can rely on SpamAssassin being loaded!!!

Changes in 2.51
Note: There was no public 2.50 release; the 2.50 version was a
private release that was available only with CanIt.

* Added "-q" option to mimedefang.  This permits the multiplexor
  to queue new incoming connections.  It may make higher utilization
  of slaves and improve throughput.

* ESMTP arguments in MAIL FROM: and RCPT TO: are now available
  to the Perl filter.  See the mimedefang-filter(5) man page for
  details.

* Documentation fixes: We don't refer to non-multiplexor mode
  any more, because that mode hasn't been available for ages.

* The "tick" facility has been enhanced to permit multiple tick
  types.  At any given instance, only one tick of a given type
  can be active, but ticks of different types can be active at
  the same time.

* Log a warning if a message has more than one Subject: header.