Zabbix

...G...PS. [ZBXNEXT-8270] added support of non-blocking sockets and thread safe connect, accept, read, write operation timeouts

Merge in ZBX/zabbix from feature/ZBXNEXT-8270-6.3 to master

* commit '3dbfee14fdc0fda3c9efff9d608d2c8a459030ea': (65 commits)
  ...G...... [ZBXNEXT-8270] fixed error handling on agent if connected host is not in allowed host list
  ...G...PS. [ZBXNEXT-8270] removed redundant code
  ...G...PS. [ZBXNEXT-8270] removed redundant assignment
  ...G...PS. [ZBXNEXT-8270] removed redundant assignments
  .......... [ZBXNEXT-8270] fixed cmocka test build with ssh
  ...G...... [ZBXNEXT-8270] fixed cGo function definition
  .......PS. [ZBXNEXT-8270] fixed misleading error message
  .......PS. [ZBXNEXT-8270] removed redundant code
  .......PS. [ZBXNEXT-8270] removed redundant alarm disabling
  ...G...PS. [ZBXNEXT-8270] removed redundant code
  ...G...PS. [ZBXNEXT-8270] fixed inconsitencies in tls read/write functions
  ...G...PS. [ZBXNEXT-8270] removed redundant assignment
  ...G...PS. [ZBXNEXT-8270] removed redundant check
  ...G...PS. [ZBXNEXT-8270] fixed return value of tls write
  ...G...PS. [ZBXNEXT-8270] fixed error handling when accepting connection
  ...G...PS. [ZBXNEXT-8270] refactored tcp write function
  .......PS. [ZBXNEXT-8270] don't try to resolve ip adresses in tcp connections
  .......PS. [ZBXNEXT-8270] removed alarm setting for java checks
  ...G...PS. [ZBXNEXT-8270] removed debug code forcing interactive auth for libssh
  ...G...PS. [ZBXNEXT-8270] fixed timeouts with libssh
  ...