NID_crl_number
X509_CRL_add1_ext_i2d(crl, NID_crl_number, tmpser, 0, 0);
crlnum = X509_CRL_get_ext_d2i(x, NID_crl_number, NULL, NULL);
{"crlNumber", "X509v3 CRL Number", NID_crl_number, 3, &so[508]},
NID_crl_number, 0, ASN1_ITEM_ref(ASN1_INTEGER),
NID_crl_number, &i, NULL);