[exim-announce] malware.c refactor headsup

I've just pushed b1f8e4, an extensive refactoring of the portion of Exim
interfacing to malware content scanners. The potential for breakage is
large as I'm not in a position to test most of the supported interfaces.

Users of the following are encouraged to keep a wary eye out for any
interesting behaviour:

f-protd
drweb
aveserver
fsecure
kavdaemon
cmdline
sophie
clamd/STREAM
clamd/zINSTREAM
mksd

Please report any seen.
--
Jeremy