Ticket 47369  version2 - provide default syntax plugin
    
        Bug Description:  syntax plugins are laoded during bootstrapping, but
                            in that phase already attributes are handled
                            eg in dse.ldif and schema files and no proper way
                            to normalize or comare values is provided.
                            This became visible with teh fix for ticket #346
                            where large attribute sets will be sorted
    
        Fix Description:   when the first attribute syntax init is done, create a plugin
                            for directory string syntax and register it with a dummy
                            attribute name. if for any attribute the syntax lookup fails
                            fall back to using this plugin.
                            It will only be used until the syntax plugins are loaded
                            and in the startup phase it is acceptable to use directory
                            string.
                            The impelemenation of the default plugin is reduce to the
                            necessary minimum not to duplicate the code of the syntax
                            plugins.
    
                            A more rigorus solution would be to refactor the code and
                            and move the common code from the syntax plugin to the
                            slapd level and reuse it in the default plugin.
                            But this would be a major change and should only be done
                            with a review of the syntax plugin code, whic could probabyly
                            be optimized.
    
        https://fedorahosted.org/389/ticket/47369
    
        Reviewed by: RichM