Update discovery and poller to allow stable interface mapping by ifName/ifDescr based port mapping.

By default libreNMS used the ifIndex to associate ports just found via SNMP
  with ports discoverd/polled before and stored in the database. On Linux boxes
  this is a problem as ifIndexes are rather likely to be unstable between reboots
  or (re)configuration of tunnel interfaces (think: GRE/OpenVPN/Tinc/...), bridges,
  Vlan interfaces, Bonding interfaces, etc.

  This patch adds a »port association mode« configuration option per device which
  allows to map discovered and known ports by their ifIndex, ifName, ifDescr, or
  maybe other means in the future.
  The default port association mode still is ifIndex for compatibility reasons.

  As port RRD files were stored by their ifIndex before, they are now identified
  by their unique and stable port_id to ensure a stable and unique mapping and
  allow future port association modes to be added without requireing any further
  internal changes. Existing RRD files are renamend accordingly in discovery and
  poller tools to ensure stability of port associations in both modules as we
  don't know which might run first after an update.

Signed-off-by: Maximilian Wilhelm <max@rfc2324.org>

scripts/tune_port.php

@@ -24,8 +24,7 @@ foreach (dbFetchRows("SELECT `device_id`,`hostname` FROM `devices` WHERE `hostna
     echo "Found hostname " . $device['hostname'].".......\n";
     foreach (dbFetchRows("SELECT `ifIndex`,`ifName`,`ifSpeed` FROM `ports` WHERE `ifName` LIKE ? AND `device_id` = ?", array('%'.$ports.'%',$device['device_id'])) as $port) {
         echo "Tuning port " . $port['ifName'].".......\n";
-        $host_rrd = $config['rrd_dir'].'/'.$device['hostname'];
-        $rrdfile = $host_rrd.'/port-'.safename($port['ifIndex'].'.rrd');
+        $rrdfile = get_port_rrdfile_path ($device['hostname'], $port['port_id']);
         rrdtool_tune('port',$rrdfile,$port['ifSpeed']);
     }
 }