Simplify flush_route.
Simplify flush_route.

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