[Dovecot] LDA null logging patch

[Joseph Tam]

> > Timo, would you consider inclusion of this patch which will skip
> > logging deliveries if deliver_log_format is empty:
> 
> Committed, slightly modified:
> http://hg.dovecot.org/dovecot-2.0/rev/0e406e7cb609

Thanks.  I tried to contribute by updating the wiki docs, but it belched
when I saved the update:

 	TextCha: Wrong answer! Go back and try again...

Here's what I tried to add at the bottom (in text mode)

 	The {{{deliver_log_format}}} specifies logging details for a successful
 	delivery.  (versions>2.0.13: leaving it empty will disable this logging).
 	See example configuration files for a full list of variable expansion:

 	{{{
 	delivery_log_format = msgid=%m: %$
 	}}}

Joseph Tam <jtam.home at gmail.com>