bug #30640 [Phpunit] fixed support for PHP 5.3 (fabpot)

This PR was merged into the 3.4 branch.

Discussion
----------

[Phpunit] fixed support for PHP 5.3

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Compat with PHP 5.3 was broken by #30496
<!--
Write a short README entry for your feature/bugfix here (replace this comment block.)
This will help people understand your PR and can be used as a start of the Doc PR.
Additionally:
 - Bug fixes must be submitted against the lowest branch where they apply
   (lowest branches are regularly merged to upper ones so they get the fixes too).
 - Features and deprecations must be submitted against the master branch.
-->

Commits
-------

606b8af [Phpunit] fixed support for PHP 5.3

src/Symfony/Bridge/PhpUnit/bin/simple-phpunit

@@ -44,11 +44,11 @@ if ('phpdbg' === PHP_SAPI) {
     $PHP .= ' -qrr';
 }
 
-$defaultEnvs = [
+$defaultEnvs = array(
     'COMPOSER' => 'composer.json',
     'COMPOSER_VENDOR_DIR' => 'vendor',
     'COMPOSER_BIN_DIR' => 'bin',
-];
+);
 
 foreach ($defaultEnvs as $envName => $envValue) {
     if ($envValue !== getenv($envName)) {