This makes the interface consistent with the changes made to the main
interface in 21483:779c0ef9682c.
Also fix some references to "struct xc_interface" which should have
been simply "xc_interface" in tools/xenpaging, and update QEMU_TAG to
pull in the corresponding qemu change.
Signed-off-by: Ian Campbell <firstname.lastname@example.org>
Signed-off-by: Ian Jackson <email@example.com>