Fix check for 172.16.0.0/12.
Fix check for 172.16.0.0/12.

boutier/babeld,woniullb/babeld,Drooids/babeld,jech/babeld,tcatm/babeld,wlanslovenija/babeld,Gwendocg/babeldToS,Gwendocg/babeldToS,sudomesh/babeld,dtaht/babeld-shortrtt-metrics,jech/babeld,wlanslovenija/babeld