Fix simta_max_message_size comparison

The default value is -1, which should result in no limit but instead
resulted in every message being rejected when no value was explicitly
set.
denser: s/IN-ADDR.ARPA/in-addr.arpa/g

Both are correct and nameservers *must* treat them identically,
but there's a widespread bug in Cisco firewalls that results in
broken reverse lookups when the request is uppercase.

Stupid Cisco.