Ticket 49016 - (un)register/migration/remove may fail if there is no suffix on 'userRoot' backend
    
    Bug Description:
        If an instance has no suffix on 'userRoot' backend, then the info structure
        may contain empty 'Suffix'.
        In fact if the last backend has no suffix (like cn=config), it overwite all
        previsously found value.
        This affect register (and possibly unregister/migrate/remove)
    
    Fix Description:
        Before overwriting the 'Suffix' value, check that the found backend contains
        'nsslapd-suffix'.
    
    https://fedorahosted.org/389/ticket/49016
    
    Reviewed by: Noriko Hosoi (Thank you Noriko)
    
    Platforms tested: RHEL 7.2
    
    Flag Day: no
    
    Doc impact: no