minor #18009 Use constant instead of function call. (Koc)

This PR was merged into the 2.3 branch.

Discussion
----------

Use constant instead of function call.

| Q             | A
| ------------- | ---
| Branch        | 2.3
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Commits
-------

c1edbc0 Use constant instead of function call.

src/Symfony/Component/Debug/Debug.php

@@ -44,7 +44,7 @@ class Debug
         error_reporting(-1);
 
         ErrorHandler::register($errorReportingLevel, $displayErrors);
-        if ('cli' !== php_sapi_name()) {
+        if ('cli' !== PHP_SAPI) {
             ExceptionHandler::register();
         // CLI - display errors only if they're not already logged to STDERR
         } elseif ($displayErrors && (!ini_get('log_errors') || ini_get('error_log'))) {

src/Symfony/Component/HttpFoundation/Request.php

@@ -242,7 +242,7 @@ class Request
         // stores the Content-Type and Content-Length header values in
         // HTTP_CONTENT_TYPE and HTTP_CONTENT_LENGTH fields.
         $server = $_SERVER;
-        if ('cli-server' === php_sapi_name()) {
+        if ('cli-server' === PHP_SAPI) {
             if (array_key_exists('HTTP_CONTENT_LENGTH', $_SERVER)) {
                 $server['CONTENT_LENGTH'] = $_SERVER['HTTP_CONTENT_LENGTH'];
             }

src/Symfony/Component/HttpKernel/DataCollector/ConfigDataCollector.php

@@ -70,7 +70,7 @@ class ConfigDataCollector extends DataCollector
             'wincache_enabled' => extension_loaded('wincache') && ini_get('wincache.ocenabled'),
             'zend_opcache_enabled' => extension_loaded('Zend OPcache') && ini_get('opcache.enable'),
             'bundles' => array(),
-            'sapi_name' => php_sapi_name(),
+            'sapi_name' => PHP_SAPI,
         );
 
         if (isset($this->kernel)) {