cipher: Add PUBKEY_FLAG_BYTE_STRING to support byte string data.
* cipher/pubkey-util.c (_gcry_pk_util_data_to_mpi): Add support for PUBKEY_FLAG_BYTE_STRING. * src/cipher.h (PUBKEY_FLAG_BYTE_STRING): New.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>