Add a new port: sysutils/sockaddr

Sockaddr is a command-line utility that makes it easy to query network
address information from the local server. With sockaddr it is possible
to create a list of the RFC 1918 addresses on a server, obtain the
default gateway, or public IP addresses and use this information in other
shell scripts. See the website for additional templating and IP math
functions.

Reviewed by: mat, swills
Approved by: swills (mentor)
Differential Revision: https://reviews.freebsd.org/D14570