Add new port: net/rpki-client

rpki-client is a FREE, easy-to-use implementation of the Resource Public Key
Infrastructure (RPKI) for Relying Parties (RP) to facilitate validation of the
Route Origin of a BGP announcement. The program queries the RPKI repository
system and outputs Validated ROA Payloads in the configuration format of either
OpenBGPD or BIRD, but also as CSV or JSON objects for consumption by other
routing stacks. rpki-client originated in OpenBSD.

This version is based on the portable version of rpki-client.

WWW: https://www.rpki-client.org/
WWW: https://github.com/rpki-client/rpki-client-portable

Allocate UID and GID 270 for use when running rpki-client.