Update maxxroutes when flushing xroutes.
Update maxxroutes when flushing xroutes.

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