INI: sssctl config-check giving the wrong message
The sssctl config-check is giving the wrong error message when
there are only snippet files and no sssd.conf.
To address this problem sss_ini code had to be partially
rewritten to allow proper configuration testing.
Resolves:
https://pagure.io/SSSD/sssd/issue/3938
Reviewed-by: Michal Židek <mzidek@redhat.com>