src: Fix a missing prototype warning.
src: Fix a missing prototype warning.

VladimirTyrin/cmocka,lsjostro/cmocka,jamesmunns/CMocka,Odie/cmocka,jhrozek/cmocka,dsch/cmocka,jschmidlapp/cmocka,wingyplus/cmocka,nuumio/cmocka,Odie/cmocka,Odie/cmocka,chadversary/cmocka,jschmidlapp/cmocka,jamesmunns/CMocka,linuxmaniac/cmocka,jschmidlapp/cmocka,VladimirTyrin/cmocka,linuxmaniac/cmocka,aleksandr-vin/cmock,aleksandr-vin/cmock,JonathonReinhart/cmocka,jhrozek/cmocka,tyc/cmocka,dsch/cmocka,chadversary/cmocka,tyc/cmocka,nuumio/cmocka,tyc/cmocka,JonathonReinhart/cmocka,lsjostro/cmocka,akikoskinen/cmocka,jhrozek/cmocka,clibs/cmocka,wingyplus/cmocka,nuumio/cmocka,clibs/cmocka