Bugfix by Henrik Mäkitaavola: check that ICMP6 process is defined before invoking it
Bugfix by Henrik Mäkitaavola: check that ICMP6 process is defined before invoking it

arurke/contiki,arurke/contiki,arurke/contiki,arurke/contiki,bluerover/6lbr,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,bluerover/6lbr,bluerover/6lbr,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,bluerover/6lbr,bluerover/6lbr,MohamedSeliem/contiki,arurke/contiki,bluerover/6lbr,bluerover/6lbr