examples/er-rest-example/resources/res-event.c: fix warning: function declaration isn't a prototype
examples/er-rest-example/resources/res-event.c: fix warning: function declaration isn't a prototype

arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,arurke/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,MohamedSeliem/contiki,arurke/contiki,arurke/contiki,arurke/contiki,MohamedSeliem/contiki,arurke/contiki,arurke/contiki