minor #15888 [Console] Fix transient HHVM test (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
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[Console] Fix transient HHVM test

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

Follow up of #15848

Commits
-------

945ec0e [Console] Fix transient HHVM test

src/Symfony/Component/Console/Tests/Helper/ProgressBarTest.php

@@ -14,9 +14,20 @@
 use Symfony\Component\Console\Helper\ProgressBar;
 use Symfony\Component\Console\Helper\Helper;
 use Symfony\Component\Console\Output\StreamOutput;
+use Symfony\Component\Console\Tests;
 
 class ProgressBarTest extends \PHPUnit_Framework_TestCase
 {
+    protected function setUp()
+    {
+        Tests\with_clock_mock(true);
+    }
+
+    protected function tearDown()
+    {
+        Tests\with_clock_mock(false);
+    }
+
     public function testMultipleStart()
     {
         $bar = new ProgressBar($output = $this->getOutputStream());