core/bitarthm: suppress false positives
core/bitarthm: suppress false positives

Co-authored-by: chrysn <8b301cba1accbd99ee84a122116d996b1f62202f@fsfe.org>

kaspar030/RIOT,kaspar030/RIOT,ant9000/RIOT,miri64/RIOT,kYc0o/RIOT,kaspar030/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,RIOT-OS/RIOT,miri64/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,jasonatran/RIOT,miri64/RIOT,ant9000/RIOT,OlegHahm/RIOT,miri64/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,kYc0o/RIOT,miri64/RIOT,jasonatran/RIOT,ant9000/RIOT,kYc0o/RIOT,jasonatran/RIOT,ant9000/RIOT,kaspar030/RIOT,OlegHahm/RIOT,kYc0o/RIOT,kaspar030/RIOT,ant9000/RIOT,RIOT-OS/RIOT,jasonatran/RIOT