[Pymilter] Small bug in py-milter on FreeBSD

[Gerhard Schmidt]

Hi

i wrote a message this morning about py-milter dying silently when an
ipv6 host connects to the Mailserver. Did some debugging since then and
found a small error in miltermodul.c that causes the module to crash
when handling IPv6 addresses.

The Problem is that on FreeBSD <arpa/inet.h> didn't get includes because
the condition for FreeBSD seams to be wrong.

The attached patch fixes the issue.

I will try to include the patch in the FreeBSD Port to fix the actual
version. But please include the fix in future releases.

Regards
   Estartu