Fix infinite loop in init when debugging is turned off

If a keychord is pressed when debugging is turned off, the main
event poll in init will return an event on the keychord fd,
but handle_keychord never reads the data.  Once this happens,
the poll will always return immediately, and init enters an
infinite loop.  Fix it by always reading from the keychord fd,
but only handling the returned keychord if debugging is
enabled.

Change-Id: Ie4efa98247d3cc978d275dc8a4516b32aa710278