We can call this qmp command to do checkpoint outside of qemu.
Xen colo will need this function.
Signed-off-by: NZhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: NWen Congyang <wencongyang@gmail.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NStefano Stabellini <sstabellini@kernel.org>