Backport type fixes

Author: nicolas-grekas

Tests/Fixtures/MockStream/MockStream.php

@@ -26,7 +26,7 @@ class MockStream
      * @param string $opened_path If the path is opened successfully, and STREAM_USE_PATH is set in options,
      *                            opened_path should be set to the full path of the file/resource that was actually opened
      */
-    public function stream_open($path, $mode, $options, &$opened_path): bool
+    public function stream_open(string $path, string $mode, int $options, string &$opened_path = null): bool
     {
         return true;
     }
@@ -37,7 +37,7 @@ public function stream_open($path, $mode, $options, &$opened_path): bool
      *
      * @return array File stats
      */
-    public function url_stat($path, $flags): array
+    public function url_stat(string $path, int $flags): array
     {
         return [];
     }