Allow anonymous bind resource limits to be set.
    
    This patch adds a new config setting named nsslapd-anonlimitsdn
    that one can set to the DN of an entry containing the bind-based
    resource limit attributes to use for operations performed by an
    anonymous user.  This allows the defaults to still be used for
    all other actual bound users who do not have any user specific
    resource settings.
    
    This implementation approach allows any resource limits that
    are registered via the reslimit API to work with this anonymous
    limits template entry.