Clang: Introduce switching/adding of warning configurations

A warning configuration is a list of command line (warning) options for
libclang. Three non-editable built-in configurations are provided by
default. The user can copy a configuration to customize it.

This is still a global setting and it changes take effect after
re-opening a document. Both issues will be addressed in follow-up
changes.

Change-Id: I86667d7dc39ad31b88666454220e6da563797740
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>
Reviewed-by: Marco Bubke <marco.bubke@theqtcompany.com>

src/plugins/cpptools/cppcodemodelsettingspage.h

@@ -39,6 +39,8 @@ QT_FORWARD_DECLARE_CLASS(QSettings)
 namespace CppTools {
 namespace Internal {
 
+class ClangDiagnosticConfigsWidget;
+
 namespace Ui { class CppCodeModelSettingsPage; }
 
 class CppCodeModelSettingsWidget: public QWidget
@@ -53,7 +55,7 @@ public:
     void applyToSettings() const;
 
 private:
-    void setupClangCodeModelWidgets() const;
+    void setupClangCodeModelWidgets();
     void setupPchCheckBox() const;
 
     bool applyClangCodeModelWidgetsToSettings() const;
@@ -61,6 +63,7 @@ private:
 
 private:
     Ui::CppCodeModelSettingsPage *m_ui;
+    QPointer<ClangDiagnosticConfigsWidget> m_clangDiagnosticConfigsWidget;
     QSharedPointer<CppCodeModelSettings> m_settings;
 };