reload iptables rules on libvirtd restart

This is the expected behaviour, I think - reloading libvirtd should
be a subset of restarting it.

Note, we reload the rules after we've determined which networks
are active (because we only add the rules for active networks)
and before we start autostart networks (to avoid re-adding the
rules).

* src/network/bridge_driver.c: reload iptables rules on startup

src/network/bridge_driver.c

@@ -259,6 +259,7 @@ networkStartup(int privileged) {
         goto error;
 
     networkFindActiveConfigs(driverState);
+    networkReloadIptablesRules(driverState);
     networkAutostartConfigs(driverState);
 
     networkDriverUnlock(driverState);