Zabbix

A.FGI..PS. [ZBXNEXT-1263] fixed number of bugs in encryption support

Before this change:
   - minimum PSK length was not enforced,
   - both TLSConnect and TLSAccept were required in agent configuration if encryption was used even for fully passive or fully active agent,
   - long network error messages were truncated,
   - too general error messages when OpenSSL did not accept peer certificate,
   - potential crash in DCsync_hosts() in case of "impossible" conditions.
After this change:
   - minimum PSK length is 128-bits,
   - TLSConnect is ignored in a fully passive agent and TLSAccept is ignored in a fully active agent,
   - increaed buffer length for reporting network socket errors,
   - more detailed error messages when OpenSSL does not accept peer certificate,
   - fixed bug in handling "impossible" conditions in DCsync_hosts().