minor symfony#21148 [PhpUnitBridge] Fix HHVM compat with putenv() (nicolas-grekas)

This PR was merged into the 3.2 branch.

Discussion
----------

[PhpUnitBridge] Fix HHVM compat with putenv()

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

On HHVM, `putenv()` is ignored by `passthru()` & co., but works with `proc_open()`.

Commits
-------

d4553c5 [PhpUnitBridge] Fix HHVM compat with putenv()

Author: nicolas-grekas

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

@@ -50,12 +50,12 @@ if (!file_exists("$PHPUNIT_DIR/phpunit-$PHPUNIT_VERSION/phpunit") || md5_file(__
     chdir("phpunit-$PHPUNIT_VERSION");
     $prevRoot = getenv('COMPOSER_ROOT_VERSION');
     putenv("COMPOSER_ROOT_VERSION=$PHPUNIT_VERSION");
-    passthru("$COMPOSER remove --no-update ".(getenv('SYMFONY_PHPUNIT_REMOVE') ?: 'phpspec/prophecy symfony/yaml'));
+    proc_close(proc_open("$COMPOSER remove --no-update ".(getenv('SYMFONY_PHPUNIT_REMOVE') ?: 'phpspec/prophecy symfony/yaml'), array(), $p));
     if (5.1 <= $PHPUNIT_VERSION && $PHPUNIT_VERSION < 5.4) {
         passthru("$COMPOSER require --no-update phpunit/phpunit-mock-objects \"~3.1.0\"");
     }
-    passthru("$COMPOSER require --no-update symfony/phpunit-bridge \">=3.2@dev\"");
-    passthru("$COMPOSER install --no-dev --prefer-dist --no-progress --ansi", $exit);
+    proc_close(proc_open("$COMPOSER require --no-update symfony/phpunit-bridge \">=3.2@dev\"", array(), $p));
+    $exit = proc_close(proc_open("$COMPOSER install --no-dev --prefer-dist --no-progress --ansi", array(), $p));
     putenv('COMPOSER_ROOT_VERSION'.(false !== $prevRoot ? '='.$prevRoot : ''));
     if ($exit) {
         exit($exit);