PKCS7_add_recipient_info
LCRYPTO_USED(PKCS7_add_recipient_info);
if (!PKCS7_add_recipient_info(p7, ri))
LCRYPTO_ALIAS(PKCS7_add_recipient_info);
int PKCS7_add_recipient_info(PKCS7 *p7, PKCS7_RECIP_INFO *ri);