LDAP: Compare lists of DNs when saving autofs entries
    
    https://fedorahosted.org/sssd/ticket/1758
    
    The autofs entries do not have the key as an unique identifier, but
    rather the full (key, value) tuple as some keys have a special meaning,
    such as the direct mount key (/-) and may be present in a single map
    multiple times.
    
    Comparing the full DN that contains both the key and the value will
    allow for working updates if either key or value changes.