If the cursor resource id isn't set the guest didn't define a cursor.
Skip the cursor update in post_load in that that case.
Reported-by: Nwanghaibin <wanghaibin.wang@huawei.com>
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>
Tested-by: Nwanghaibin <wanghaibin.wang@huawei.com>
Message-id: 20170710070432.856-1-kraxel@redhat.com
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>