Slightly simplify logic for sending txcost.
Slightly simplify logic for sending txcost.

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