[master] Fix issues reported by static analyse

Author: romainneutron

DependencyInjection/Compiler/CachePoolClearerPass.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler;
 
+use Symfony\Component\Cache\Adapter\AbstractAdapter;
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Reference;