TextEditor: Fix memory leak in CircularClipboardAssist

Change-Id: Ib32d7f4c25c9012fbcb76db9e3af7446cf0a2505
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>

src/plugins/texteditor/circularclipboardassist.cpp

@@ -91,6 +91,7 @@ public:
     {
         if (!interface)
             return 0;
+        const QScopedPointer<const AssistInterface> AssistInterface(interface);
 
         QIcon icon = QIcon::fromTheme(QLatin1String("edit-paste"), QIcon(QLatin1String(Core::Constants::ICON_PASTE))).pixmap(16);
         CircularClipboard * clipboard = CircularClipboard::instance();