Help: Pass const list by reference

Change-Id: I00ece6d5c41a9067bd12b388bf9ca5f80e981ed6
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/help/docsettingspage.cpp

@@ -177,7 +177,7 @@ bool DocSettingsPage::eventFilter(QObject *object, QEvent *event)
     return IOptionsPage::eventFilter(object, event);
 }
 
-void DocSettingsPage::removeDocumentation(const QList<QListWidgetItem*> items)
+void DocSettingsPage::removeDocumentation(const QList<QListWidgetItem*> &items)
 {
     if (items.isEmpty())
         return;

src/plugins/help/docsettingspage.h

@@ -55,7 +55,7 @@ private slots:
 
 private:
     bool eventFilter(QObject *object, QEvent *event);
-    void removeDocumentation(const QList<QListWidgetItem*> items);
+    void removeDocumentation(const QList<QListWidgetItem *> &items);
     void addItem(const QString &nameSpace, const QString &fileName);
 
 private: