MAGETWO-54054: Compiler performance optimization

 - MAGETWO-50778: Minor code style fix
 - MAGETWO-57139: Minor code style fix

lib/internal/Magento/Framework/Module/Dir/Reader.php

@@ -95,7 +95,7 @@ class Reader
     /**
      * Retrieve iterator for files with $filename from components located in component $subDir.
      *
-     * @param $filename
+     * @param string $filename
      * @param string $subDir
      *
      * @return FileIterator

setup/src/Magento/Setup/Console/Command/DiCompileCommand.php

@@ -203,7 +203,7 @@ class DiCompileCommand extends Command
      * @param string[] $modulePaths
      * @return string[]
      */
-    private function getExcludedModulePaths($modulePaths)
+    private function getExcludedModulePaths(array $modulePaths)
     {
         $modulesByBasePath = [];
         foreach ($modulePaths as $modulePath) {
@@ -237,7 +237,7 @@ class DiCompileCommand extends Command
      * @param string[] $libraryPaths
      * @return string[]
      */
-    private function getExcludedLibraryPaths($libraryPaths)
+    private function getExcludedLibraryPaths(array $libraryPaths)
     {
         $excludedLibraryPaths = [
             '#^(?:' . join('|', $libraryPaths) . ')/([\\w]+/)?Test#',