Zabbix

.......PS. [ZBXNEXT-8567] added asynchronous DNS resolving for async SNMP and Zabbix agent pollers

Merge in ZBX/zabbix from feature/ZBXNEXT-8620-6.5 to master

* commit 'ae23f5ca4fe6fb4eaba3b0920841eb458bbea7b1':
  .......PS. [ZBXNEXT-8620] added ChangeLog entry
  .......PS. [ZBXNEXT-8620] fixed DNS not being resolved for non walk snmp items
  .......PS. [ZBXNEXT-8567] avoid DNS resolving for IP address
  .......PS. [ZBXNEXT-8567] avoid initializing DNS for HTTP agent poller
  .......PS. [ZBXNEXT-8567] improved async poller cleanup
  .......PS. [ZBXNEXT-8567] fixed build when libevent is not available
  .......PS. [ZBXNEXT-8567] added asynchronous DNS resolving for async SNMP and Zabbix agent pollers
  .......PS. [ZBXNEXT-8567] added asynchronous DNS resolving for async SNMP and Zabbix agent pollers