[Exim] exiscan-acl-4.31-16

The patch against the newly released Exim 4.31 is at

http://duncanthrax.net/exiscan-acl/

No functional changes, just adapted the patch. To those awaiting replies
to their suggestions/patches: Please show even more patience :)

BTW, the distro maintainers can include -16 in their binary
redistributions now, it looks pretty stable (no bug reports yet).

regards,

/tom