Zabbix

.......... [DEV-2106] moved zbxdbconfigworker library out of public scope, made sure zbxpreproc library has single public interface, added _proxy and _server postfixes for housekeeper and stats libraries

Merge in ZBX/zabbix from feature/DEV-2106-6.5 to master

* commit '3aaa6f4c84c55728a434192c83d4d4e76ffe2dab':
  .......... [DEV-2106] clarified headers for stats private libraries in server and proxy
  .......... [DEV-2106] added _proxy and _server postfixes to housekeeper private libraries
  .......... [DEV-2106] fixed build
  .......... [DEV-2106] created separate directory for zbxpreprocbase library
  .......... [DEV-2106] fixed build 4
  .......... [DEV-2106] fixed build 3
  .......... [DEV-2106] fixed build
  .......... [DEV-2106] fixed build
  .......... [DEV-2106] moved zbxdbconfigworker library out of public scope