fixed gcc 8 compiler waring
fixed gcc 8 compiler waring

closes https://github.com/OpenSC/OpenSC/pull/1474

dengert/OpenSC,hongquan/OpenSC-main,rickyepoderi/OpenSC,CardContact/OpenSC,fabled/OpenSC,LudovicRousseau/OpenSC,viktorTarasov/OpenSC-SM,Jakuje/OpenSC,fabled/OpenSC,hhonkanen/OpenSC,Jakuje/OpenSC,philipWendland/OpenSC,LudovicRousseau/OpenSC,rickyepoderi/OpenSC,AktivCo/OpenSC,philipWendland/OpenSC,frankmorgner/OpenSC,LudovicRousseau/OpenSC,dengert/OpenSC,viktorTarasov/OpenSC-SM,hongquan/OpenSC-main,mouse07410/OpenSC,CardContact/OpenSC,philipWendland/OpenSC,metsma/OpenSC,OpenSC/OpenSC,CardContact/OpenSC,frankmorgner/OpenSC,OpenSC/OpenSC,mouse07410/OpenSC,rickyepoderi/OpenSC,AktivCo/OpenSC,mouse07410/OpenSC,hhonkanen/OpenSC,OpenSC/OpenSC,Jakuje/OpenSC,metsma/OpenSC,frankmorgner/OpenSC,hongquan/OpenSC-main,AktivCo/OpenSC,metsma/OpenSC,fabled/OpenSC,fabled/OpenSC,viktorTarasov/OpenSC-SM,dengert/OpenSC,hhonkanen/OpenSC,frankmorgner/OpenSC,Jakuje/OpenSC