Zabbix

.......PS. [DEV-4407] fixed memory leak in preprocessing manager on shutdown, removed redundant variable assignment, fixed includes

Merge in ZBX/zabbix from feature/DEV-4407-7.5 to master

* commit '2da53ebedbfeda381c2fd0f22831fa1377684d43':
  .......PS. [DEV-4407] removed redundant variable assignment
  .......PS. [DEV-4407] fixed item task tracker queue cleanup on exit
  .......PS. [DEV-4407] fixed includes