make: add -ffunction-sections -fdata-sections to LINKFLAGS if LTO=1
make: add -ffunction-sections -fdata-sections to LINKFLAGS if LTO=1

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