ClangTools: Modernize

modernize-use-nullptr
modernize-use-override
modernize-use-equals-default

Change-Id: I14a840c6f2972f57763cdfd4bb4483df1ec261d4
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/clangtools/clangtoolsplugin.cpp

@@ -82,19 +82,19 @@ public:
         setCategoryIcon(Analyzer::Icons::SETTINGSCATEGORY_ANALYZER);
     }
 
-    QWidget *widget()
+    QWidget *widget() override
     {
         if (!m_widget)
             m_widget = new ClangToolsConfigWidget(ClangToolsSettings::instance());
         return m_widget;
     }
 
-    void apply()
+    void apply() override
     {
         ClangToolsSettings::instance()->writeSettings();
     }
 
-    void finish()
+    void finish() override
     {
         delete m_widget;
     }