examples: Fix warnings of customer_database.
examples: Fix warnings of customer_database.

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