tools/lib/atben.c: added support for interrupt_wait (polled)
tools/lib/atben.c: added support for interrupt_wait (polled)

- atben.c (atben_interrupt_wait): loop until either the timeout has
  been reached or an interrupt has occurred
- atben.c (atben_driver): added atben_interrupt_wait

cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan,cfriedt/ben-wpan