Add copyright statement to kernel.c.
Add copyright statement to kernel.c.

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