If we enable interrupts for the serial console, add a proper interrupt
handler.  Since we don't know what vector we'll end up using, or if we
are shared with other devices, simply hook *all* the interrupts and
poll the serial port then.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Impact: new feature

COMBOOT interface to the new shuffler; resurrect comapi_chainboot as
that functionality is still potentially relevant.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Move source files out of the root directory; the root is a mess and
has become virtually unmaintainable.  The Syslinux core now lives in
core/; the Linux and generic utilities has moved into utils/, and
copybs.com has moved into dos/; it had to go somewhere, and it seemed
as good a place as any.