gluon-mesh-batman-adv: Do not add local-if to respondd
If there are local services running on an interface that sits on top of bat0 these interfaces may be added to the translocal batman-table. Contrary to the bat0-interface itself this entries are not marked with the TT_CLIENT_NOPURGE -flag and are thus added to the client-count reported by respondd. In this case the client-count reported is one too high. This change adds an additional check to the function doing the actual counting. This check makes sure that no local interface is counted as a client. Since respondd only collects data in an interval of minutes (depending on the site's configuration) the additional costs for this check should be negligible.