Update postfix package to 2.8.4.

Postfix stable release 2.8.4 is available. This contains fixes and
workarounds that were already included with the Postfix 2.9
experimental release. Where applicable these fixes will also be
made available for the legacy releases Postfix 2.5..2.7.

    * Performance: a high load of DSN success notification requests
      could slow down the queue manager. Solution: make the trace
      client asynchronous, just like the bounce and defer clients.

    * The local(8) delivery agent ignored table lookup errors in
      mailbox_command_maps, mailbox_transport_maps, fallback_transport_maps
      and (while bouncing mail to alias) alias owner lookup.

    * Workaround: dbl.spamhaus.org rejects lookups with "No IP
      queries" even if the name has an alphanumerical prefix. We
      play safe, and skip both RHSBL and RHSWL queries for names
      ending in a numerical suffix.

    * The "sendmail -t" command reported "protocol error" instead
      of "file too large", "no space left on device" etc.

    * The Postfix Milter client reported a temporary error instead
      of "file too large" in three cases.

    * Linux kernel version 3 support. Linus Torvalds has reset the
      counters for reasons not related to changes in code.

You can find the updated Postfix source code at the mirrors listed
at http://www.postfix.org/.

(taca)