Problem description: in case if Zabbix agent2 is launched with Admin rights (via sudo), it returnsincorrect value (by 1 more) for the "system.users.num" metric.
The same problem is observed on windows even without admin rights.

Steps to reproduce:

1. Run zabbix_agent2 via sudo (with admin rights)
2. Open the list of items of a host with corresponding agent interface
3. Press "Create item" button
4. In the opened form set "Key" = "system.users.num"
5. Press "Test" button
6. In the opened Item test dialog press "Get value and test" button

Result: The returned value is by 1 more than the actual number of users that are logged in (2 instead of 1).
Expected: Same as in the case of the regular agent (also launched with admin rights) the number returned by the metric should coincide with the number of users that are logged in.