tls13_cert_add
if (!tls13_cert_add(ctx, &cert_list, cpk->x509, tlsext_client_build))
if (!tls13_cert_add(ctx, &cert_list, cert, tlsext_client_build))
int tls13_cert_add(struct tls13_ctx *ctx, CBB *cbb, X509 *cert,
if (!tls13_cert_add(ctx, &cert_list, cpk->x509, tlsext_server_build))
if (!tls13_cert_add(ctx, &cert_list, cert, NULL))