minor #21463 [HttpKernel] DebugHandlersListener micro optimize (SpacePossum)

This PR was merged into the 3.2 branch.

Discussion
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[HttpKernel] DebugHandlersListener micro optimize

| Q             | A
| ------------- | ---
| Branch?       | 3.2 (lowest version introduced)
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

For ref.: [php_sapi_name()](http://php.net/manual/en/function.php-sapi-name.php) returns the const `PHP_SAPI`.

This a PR out of courtesy to see if the CS/Fixer/Rule that found this case should be added to the SF set by default.

Commits
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f9f862f Update DebugHandlersListener.php

src/Symfony/Component/HttpKernel/EventListener/DebugHandlersListener.php

@@ -137,7 +137,7 @@ class DebugHandlersListener implements EventSubscriberInterface
     {
         $events = array(KernelEvents::REQUEST => array('configure', 2048));
 
-        if ('cli' === php_sapi_name() && defined('Symfony\Component\Console\ConsoleEvents::COMMAND')) {
+        if ('cli' === PHP_SAPI && defined('Symfony\Component\Console\ConsoleEvents::COMMAND')) {
             $events[ConsoleEvents::COMMAND] = array('configure', 2048);
         }