Zabbix

...G...... [ZBX-17716] fixed 'UserParameter' parsing and possible buffer overrun

Merge in ZBX/zabbix from feature/ZBX-18568-5.0 to release/5.0

* commit '879d9237c45659789432608289899f45cbfdd09a':
  .D........ [ZBX-18568] added ChangeLog entry
  ...G...... [ZBX-18568] removed redundant check
  ...G...... [ZBX-18568] fixed possible buffer overrun on the original agent
  ...G...... [ZBX-18568] fixed agent 2 'UserParameter' parsing to match the original agent
  ...G...... [ZBX-18568] removed unnecessary check
  ...G...... [ZBX-18568] fixed Agent2 'UserParameter' parsing