bug symfony#25027 [FrameworkBundle] Hide server:log command based on deps (sroze)

This PR was merged into the 3.4 branch.

Discussion
----------

[FrameworkBundle] Hide server:log command based on deps

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#25025
| License       | MIT
| Doc PR        | ø

Remove the `server:log` command if monolog is not installed.

Commits
-------

b505ac7 Remove the `server:log` command if monolog is not loaded

Author: nicolas-grekas

src/Symfony/Bundle/WebServerBundle/DependencyInjection/WebServerExtension.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\WebServerBundle\DependencyInjection;
 
+use Symfony\Bridge\Monolog\Formatter\ConsoleFormatter;
 use Symfony\Component\DependencyInjection\Extension\Extension;
 use Symfony\Component\DependencyInjection\Loader\XmlFileLoader;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
@@ -25,5 +26,9 @@ public function load(array $configs, ContainerBuilder $container)
     {
         $loader = new XmlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));
         $loader->load('webserver.xml');
+
+        if (!class_exists(ConsoleFormatter::class)) {
+            $container->removeDefinition('web_server.command.server_log');
+        }
     }
 }