Relicence files with kind permission from the following contributors:

  Alex Williamson <alex.williamson@redhat.com>
  Eduardo Habkost <ehabkost@redhat.com>
  Greg Jednaszewski <jednaszewski@gmail.com>
  H. Peter Anvin <hpa@zytor.com>
  Marin Hannache <git@mareo.fr>
  Robin Smidsrød <robin@smidsrod.no>
  Shao Miller <sha0.miller@gmail.com>
  Thomas Horsten <thomas@horsten.com>

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Modified-by: Michael Brown <mcb30@ipxe.org>
Signed-off-by: Marin Hannache <git@mareo.fr>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Abstract out the ability to reboot the system to a separate reboot()
function (with platform-specific implementations), add an EFI
implementation, and make the existing "reboot" command available under
EFI.

Signed-off-by: Michael Brown <mcb30@ipxe.org>