Zabbix

...G...PS. [ZBXNEXT-1263] added recognizing of TLS parameters if compiled without TLS support

Before:
    - If TLS support was not compiled in then TLS parameters were reported as unknown.
After:
   - If TLS support is not compiled in then TLS parameters are recognized and error message is issued
     about TLS support not compiled in,
   - unnecessary code removed from 'zabbix_get',
   - minor fix in 'zabbix_sender' and 'zabbix_get' error messages,
   - minor fix in comments.