Cope with opaque structs in <openssl/x509.h>

Index: src/server/ca.c
--- src/server/ca.c.orig
+++ src/server/ca.c
@@ -568,7 +568,7 @@ int ca_x509_verify_crl(struct conf **confs,
 		revoked=(X509_REVOKED *)
 			sk_X509_REVOKED_value(X509_CRL_get_REVOKED(crl), i);
 		if(!ASN1_INTEGER_cmp(
-#if OPENSSL_VERSION_NUMBER < 0x1010000fL || defined(LIBRESSL_VERSION_NUMBER)
+#if OPENSSL_VERSION_NUMBER < 0x1010000fL
 			revoked->serialNumber,
 #else
 			X509_REVOKED_get0_serialNumber(revoked),
