zabbix50-server: Import zabbix-server 5.0.5

Zabbix is the ultimate enterprise-level software designed for monitoring
availability and performance of IT infrastructure components. Zabbix is open
source and comes at no cost.

With Zabbix it is possible to gather virtually limitless types of data from
the network. High performance real-time monitoring means that tens of thousands
of servers, virtual machines and network devices can be monitored
simultaneously. Along with storing the data, visualization features are
available (overviews, maps, graphs, screens, etc), as well as very flexible
ways of analyzing the data for the purpose of alerting.

This is an LTS release of Zabbix!

(otis)