Repocopy from net-mgmt/cacti-spine (r419786) -> net-mgmt/cacti88-spine

Multithreaded poller for Cacti written in C

New releases of Cacti are still unable to work with useful plugins like
"GPS Map" and "Network Weathermap".

PR: 219686
Submitted by: Vinicius Zavam <egypcio@googlemail.com>
Approved by: garga (mentor)
Differential Revision: https://reviews.freebsd.org/D11024