OpenSSL: Write PKCS#12 extra cert errors into debug log

Commit de2a7b796d82d92120aa9532450863f503e1885a ('OpenSSL: Use
connection certificate chain with PKCS#12 extra certs') added a new
mechanism for doing this with OpenSSL 1.0.2 and newer. However, it did
not poinr out anything in debug log if SSL_add1_chain_cert() failed. Add
such a debug print and also silence static analyzer warning on res being
stored without being read (since the error case is ignored at least for
now).

Signed-off-by: Jouni Malinen <j@w1.fi>

src/crypto/tls_openssl.c

@@ -2237,10 +2237,15 @@ static int tls_parse_pkcs12(struct tls_data *data, SSL *ssl, PKCS12 *p12,
 			wpa_printf(MSG_DEBUG, "TLS: additional certificate"
 				   " from PKCS12: subject='%s'", buf);
 			if (SSL_add1_chain_cert(ssl, cert) != 1) {
+				tls_show_errors(MSG_DEBUG, __func__,
+						"Failed to add additional certificate");
 				res = -1;
 				break;
 			}
 		}
+		if (!res) {
+			/* Try to continue anyway */
+		}
 		sk_X509_free(certs);
 #ifndef OPENSSL_IS_BORINGSSL
 		res = SSL_build_cert_chain(ssl,