sys/arduino: add interrupts/noInterrupts
sys/arduino: add interrupts/noInterrupts

This fixes the error:

$ BOARD=arduino-mega2560 make -C tests/pkg_arduino_sdi_12/
[...]
[...]/RIOT/build/pkg/arduino_sdi_12/src/SDI12.cpp:379:7: error: ‘interrupts’ was not declared in this scope

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