bug #20132 Use "more entropy" option for uniqid() (javiereguiluz)

This PR was squashed before being merged into the 2.7 branch (closes #20132).

Discussion
----------

Use "more entropy" option for uniqid()

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

As you can see in [the source code of the PHP uniqid() function](https://github.com/php/php-src/blob/1c295d4a9ac78fcc2f77d6695987598bb7abcb83/ext/standard/uniqid.c#L68) when you don't pass `true` as the second argument, PHP sleeps the application for 1 microsecond (`usleep(1)`)

Symfony uses `true` almost everywhere, but there are still some places (mostly in bundles) where this is not the case.

Commits
-------

4403e28 Use "more entropy" option for uniqid()

src/Symfony/Bridge/ProxyManager/Tests/LazyProxy/PhpDumper/ProxyDumperTest.php

@@ -86,7 +86,7 @@ public function getProxyCandidates()
         $definitions = array(
             array(new Definition(__CLASS__), true),
             array(new Definition('stdClass'), true),
-            array(new Definition('foo'.uniqid()), false),
+            array(new Definition(uniqid('foo', true)), false),
             array(new Definition(), false),
         );
 

src/Symfony/Bridge/Twig/Command/LintCommand.php

@@ -109,7 +109,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 $template .= fread(STDIN, 1024);
             }
 
-            return $this->display($input, $output, array($this->validate($twig, $template, uniqid('sf_'))));
+            return $this->display($input, $output, array($this->validate($twig, $template, uniqid('sf_', true))));
         }
 
         $filesInfo = $this->getFilesInfo($twig, $filenames);