Deprecate NTLMv1 proxy auth method.

Deprecate NTLMv1 proxy auth method.

NTLMv1 is ancient and not considered secure anymore and we are not
aware of any users or software still requiring this feature.

Additionally it currently depends on our "doing single DES using
3DES" workaround for OpenSSL (cipher_des_encrypt_ecb). So removing
NTLMv1 will also allow us to remove that workaround.

Reported-By: Trial of Bits (TOB-OVPN-7)
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20221215190143.2107896-9-arne@rfc2549.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg25731.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>