altoslib: Pass InterruptedException up the stack instead of hiding it

When interrupting a thread that is talking to a serial device, it's
important not to have that thread discard the InterruptedException so
that it will actually terminate. This patch removes a bunch of places
that were discarding InterruptedExceptions and lets higher level code
see them so that they can exit cleanly.

Signed-off-by: Keith Packard <keithp@keithp.com>