Make neigh->hello_seqno a short.
Make neigh->hello_seqno a short.

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