Add bulk function interface for OFB mode
* cipher/cipher-internal.h (cipher_bulk_ops): Add 'ofb_enc'. * cipher/cipher-ofb.c (_gcry_cipher_ofb_encrypt): Use bulk encryption function if defined. * cipher/basic.c (check_bulk_cipher_modes): Add OFB-AES test vectors.
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>