[NEW] net/dbip

Hi ports@,

Here is a new port: net/dbip.

Following the decision from MaxMind [1] to stop releasing their GeoLite2
databases under a Creative Commons license, I have been looking for an
alternative we could package.

DB-IP has provided free databases in CSV format for a while now, and are
now also providing the databases in MMDB format which can be directly
consumed with net/libmaxminddb. These databases are licensed under the
Creative Commons Attribution 4.0 International License (CC BY 4.0).

They are not a full replacement for GeoLite2 yet, as there is no free
version of the IP to ASN database at the moment.

Comments? OK?

[1] https://blog.maxmind.com/2019/12/18/significant-changes-to-accessing-and-using-geolite2-databases/