This allows any QEMU binary to be executed with:
$QEMU_BINARY -M none -qmp stdio
Without errors from missing options that are required by various boards. This
also provides a mode that we can use in the future to construct machines
entirely through QMP commands.
Cc: Daniel Berrange <berrange@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>