[Exim] Exiscan for Exim 4.24

Hello,

for those like me, who can't wait until Tom is back, I modified
exiscan-acl-4.22-12 for exim 4.24. Here it is, together with my own
patch, which extends exiscan by multiple spamd servers and full caching:

http://www.moria.de/~michael/exim/

In case this patch breaks anything for you, you get to keep all pieces
and have to wait until an official release, but it works for me. ;)

Michael