Libgcrypt and nettle support 3des-ede, so this patch add 3des-ede
support when using libgcrypt or nettle.

Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>