bug #16182 [Process] Workaround buggy PHP warning (cbj4074)

This PR was submitted for the 2.8 branch but it was merged into the 2.3 branch instead (closes #16182).

Discussion
----------

[Process] Workaround buggy PHP warning

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

This temporary workaround is intended to address an uncaught exception that may occur, until https://bugs.php.net/bug.php?id=69240 is fixed.

Obviously the `@` operator is another option, but I'm erring towards the notion that the Symfony authors/maintainers may wish to implement more elegant exception-handling logic than simply using `@`.

Commits
-------

b1bd093 [Process] Workaround buggy PHP warning

src/Symfony/Component/Process/ExecutableFinder.php

@@ -56,7 +56,8 @@ public function find($name, $default = null, array $extraDirs = array())
             $searchPath = explode(PATH_SEPARATOR, ini_get('open_basedir'));
             $dirs = array();
             foreach ($searchPath as $path) {
-                if (is_dir($path)) {
+                // Silencing against https://bugs.php.net/69240
+                if (@is_dir($path)) {
                     $dirs[] = $path;
                 } else {
                     if (basename($path) == $name && is_executable($path)) {