Only fields that are allowed by RFC 5755 are
accessible through this API. Fields that are only supported
in version 1 attribute certificates (e.g. the AttCertIssuer
v1Form fields) are not implemented.
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/15857)
