=head1 HISTORY
-X509_get_version(), X509_set_version() X509_REQ_get_version(),
-X509_REQ_set_version(), X509_REQ_get_version() and X509_REQ_set_version()
-are available in all versions of OpenSSL.
-
X509_get_version(), X509_REQ_get_version() and X509_CRL_get_version() are
functions in OpenSSL 1.1.0, in previous versions they were macros.