Fix comparison between signed and unsigned warning.
Fix comparison between signed and unsigned warning.

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