Fix return value of _php_server_push_callback in case of failure

It should return CURL_PUSH_DENY by default instead of CURL_PUSH_OK in
the branch I added, just like the check above.
I forgot to change this after doing tests.

Author: nielsdos

ext/curl/multi.c

@@ -384,7 +384,7 @@ static int _php_server_push_callback(CURL *parent_ch, CURL *easy, size_t num_hea
 
 	if (UNEXPECTED(zend_fcall_info_init(&t->func_name, 0, &fci, &t->fci_cache, NULL, NULL) == FAILURE)) {
 		php_error_docref(NULL, E_WARNING, "Cannot call the CURLMOPT_PUSHFUNCTION");
-		return CURL_PUSH_OK;
+		return rval;
 	}
 
 	parent = Z_CURL_P(pz_parent_ch);