boards/native: Default to C11 instead of C99
boards/native: Default to C11 instead of C99

RIOT-OS/RIOT,jasonatran/RIOT,kYc0o/RIOT,authmillenon/RIOT,kYc0o/RIOT,kaspar030/RIOT,OlegHahm/RIOT,miri64/RIOT,aeneby/RIOT,yogo1212/RIOT,OTAkeys/RIOT,basilfx/RIOT,OlegHahm/RIOT,kaspar030/RIOT,toonst/RIOT,OlegHahm/RIOT,ant9000/RIOT,toonst/RIOT,miri64/RIOT,toonst/RIOT,josephnoir/RIOT,ant9000/RIOT,jasonatran/RIOT,jasonatran/RIOT,basilfx/RIOT,josephnoir/RIOT,kYc0o/RIOT,kYc0o/RIOT,x3ro/RIOT,josephnoir/RIOT,authmillenon/RIOT,x3ro/RIOT,mtausig/RIOT,smlng/RIOT,aeneby/RIOT,mtausig/RIOT,OlegHahm/RIOT,jasonatran/RIOT,ant9000/RIOT,authmillenon/RIOT,mtausig/RIOT,miri64/RIOT,x3ro/RIOT,josephnoir/RIOT,authmillenon/RIOT,ant9000/RIOT,jasonatran/RIOT,kYc0o/RIOT,kaspar030/RIOT,aeneby/RIOT,basilfx/RIOT,yogo1212/RIOT,ant9000/RIOT,smlng/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,basilfx/RIOT,aeneby/RIOT,smlng/RIOT,OTAkeys/RIOT,toonst/RIOT,josephnoir/RIOT,yogo1212/RIOT,kaspar030/RIOT,kaspar030/RIOT,mtausig/RIOT,miri64/RIOT,x3ro/RIOT,aeneby/RIOT,RIOT-OS/RIOT,miri64/RIOT,yogo1212/RIOT,x3ro/RIOT,authmillenon/RIOT,OTAkeys/RIOT,mtausig/RIOT,yogo1212/RIOT,smlng/RIOT,basilfx/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,toonst/RIOT,smlng/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,yogo1212/RIOT