Fix tests for GnuTLS

[dilyanpalauzov]

diff --git a/libopendkim/dkim.c b/libopendkim/dkim.c
--- a/libopendkim/dkim.c
+++ b/libopendkim/dkim.c
@@ -5693,8 +5693,6 @@ dkim_sig_process(DKIM *dkim, DKIM_SIGINFO *sig)
                vstat = gnutls_pubkey_verify_hash(crypto->crypto_pubkey, 0,
                                                  &crypto->crypto_digest,
                                                  &crypto->crypto_sig);
-               if (vstat < 0)
-                       dkim_sig_load_ssl_errors(dkim, sig, vstat);
 # else /* GNUTLS_VERSION_MAJOR == 2 */
                hash = dkim_libfeature(dkim->dkim_libhandle,
                                       DKIM_FEATURE_SHA256);
@@ -5709,9 +5707,12 @@ dkim_sig_process(DKIM *dkim, DKIM_SIGINFO *sig)
                                                   signalg, 0,
                                                   &crypto->crypto_digest,
                                                   &crypto->crypto_sig);
+# endif /* GNUTLS_VERSION_MAJOR == 2 */
                if (vstat < 0)
                        dkim_sig_load_ssl_errors(dkim, sig, vstat);
-# endif /* GNUTLS_VERSION_MAJOR == 2 */
+               else
+                       /* OpenSSL’s RSA_verify returns 1 on success, so we normalize vstat here */
+                       vstat = 1;

                (void) gnutls_pubkey_get_pk_algorithm(crypto->crypto_pubkey,
                                                      &crypto->crypto_keysize);

[mskucherawy]

Can you please submit these as pull requests? Extracting them to apply manually is error-prone.