rpl_print_neighbor_list(): cast clock_time_t to unsigned for portable printout
rpl_print_neighbor_list(): cast clock_time_t to unsigned for portable printout

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