bug #27236 [Filesystem] Fix usages of error_get_last() (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
----------

[Filesystem] Fix usages of error_get_last()

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Same as #27232 for 2.7.
When a userland error handler doesn't return `false`, `error_get_last()` is not updated, so we cannot see the real last error, but the previous one.

See https://3v4l.org/Smmt7

Commits
-------

9d015c7c50 [Filesystem] Fix usages of error_get_last()

Author: fabpot

SplFileInfo.php

@@ -66,12 +66,11 @@ public function getRelativePathname()
      */
     public function getContents()
     {
-        $level = error_reporting(0);
+        set_error_handler(function ($type, $msg) use (&$error) { $error = $msg; });
         $content = file_get_contents($this->getPathname());
-        error_reporting($level);
+        restore_error_handler();
         if (false === $content) {
-            $error = error_get_last();
-            throw new \RuntimeException($error['message']);
+            throw new \RuntimeException($error);
         }
 
         return $content;