crypto: accumulative hashing API

crypto: accumulative hashing API

Changes the hash API to support accumulative hashing.
Hash objects are created with "qcrypto_hash_new",
updated with data with "qcrypto_hash_update", and
the hash obtained with "qcrypto_hash_finalize".

These changes bring the hashing API more in line with the
hmac API.

Signed-off-by: Alejandro Zeise <alejandro.zeise@seagate.com>
[ clg: - Changed documentation "non-zero on error" -> "-1 on error" ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>