delay () for Due doesn't handle 32-bit wrap-around.

[MarkTillotson]

In 1.5.4, 1.5.5

See http://forum.arduino.cc/index.php?topic=204081.0

The existing delay() implementation uses an unsigned comparison between GetTickCount() and a target timestamp,
rather than correctly comparing a timestamp difference to
an interval.

The existing code could (in admittedly rare circumstances) simply hang forever (should the variable end happen to be zero).

[cmaglie]

Fixed. Thank you!

C