MAGETWO-33132: Uninstall Logic Won't Clean Caches Properly

- added use for FileSystemException

Author: Ivan Gavryshko

lib/internal/Magento/Framework/App/State/CleanupFiles.php

@@ -7,6 +7,7 @@
 namespace Magento\Framework\App\State;
 
 use Magento\Framework\Filesystem;
+use Magento\Framework\Exception\FileSystemException;
 use Magento\Framework\App\Filesystem\DirectoryList;
 
 /**