Add accessor for x509.cert_info.

(Imported from upstream's 519ad9b3845c475d29db8b84b59bde7edecb4e70.)

crypto/x509/x509.h

diff --git a/crypto/x509/x509.h b/crypto/x509/x509.h
index c4e742e..7aeb171 100644
--- a/crypto/x509/x509.h
+++ b/crypto/x509/x509.h
@@ -575,6 +575,7 @@
 /* #define	X509_get_serialNumber(x) ((x)->cert_info->serialNumber) */
 #define		X509_get_notBefore(x) ((x)->cert_info->validity->notBefore)
 #define		X509_get_notAfter(x) ((x)->cert_info->validity->notAfter)
+#define		X509_get_cinf(x) ((x)->cert_info)
 #define		X509_extract_key(x)	X509_get_pubkey(x) /*****/
 #define		X509_REQ_get_version(x) ASN1_INTEGER_get((x)->req_info->version)
 #define		X509_REQ_get_subject_name(x) ((x)->req_info->subject)