Zabbix

.......PS. [ZBXNEXT-8166] reworked preprocessing manager to use worker threads instead of processes

Merge in ZBX/zabbix from feature/ZBXNEXT-8166-6.3 to master

* commit '2a3b06743c03e7569a848194de405da8fbb3639d': (50 commits)
  .......PS. [ZBXNEXT-8166] removed comment
  .......PS. [ZBXNEXT-8166] fixed zbx_strerror thread safety issues
  .......PS. [ZBXNEXT-8166] fixed preprocessing configuration refresh for hosts without macros
  .......PS. [ZBXNEXT-8166] fixed 'notsupported' item value handling in item/preprocessing tests
  .......PS. [ZBXNEXT-8166] fixed memory leak in item testing without preprocessing
  .......PS. [ZBXNEXT-8166] fixed warnings
  .......PS. [ZBXNEXT-8166] moved timekeeper update outside queue lock
  .......PS. [ZBXNEXT-8166] updated copyright dates
  .......PS. [ZBXNEXT-8166] changed preprocessing worker thread starting/ending log message
  .......PS. [ZBXNEXT-8166] improved flush interval detection
  .......... [ZBXNEXT-8166] fixed test case
  .......PS. [ZBXNEXT-8166] reverted ".......PS. [ZBXNEXT-8166] added task task queue unlocking when creating preprocessing tasks for dependent items"
  .......PS. [ZBXNEXT-8166] batch task creation from incoming requests and queue it with single lock
  .......PS. [ZBXNEXT-8166] added task task queue unlocking when creating preprocessing tasks for dependent items
  .......PS. [ZBXNEXT-8166] free queued tasks when destroying task queue
  .......PS. [ZBXNEXT-8166] fixed timekeeper stat gathering
  .......PS. [ZBXNEXT-8166] fixed worker registering
  .......PS. [ZBXNEXT-8166] fixed worker notifications and queue locking
  .......PS. [ZBXNEXT-8166] fixed task queue locking
  .......... [ZBXNEXT-8166] fixed cmocka test build
  ...