Code model: Update on changes from the versioning system.

Add state logic to CppCodeModelManagerInterface, making it aware whether
an indexer is running, protect the update methods from another
invocation while running. Add changed signals to IVersionControl and
VCSManager and wire them to the update methods. Add a menu action for
manually updating.

Reviewed-by: Roberto Raggi <roberto.raggi@nokia.com>
Reviewed-by: con <qtc-committer@nokia.com>

src/plugins/cpptools/cppmodelmanager.h

@@ -111,6 +111,8 @@ public:
     void setHeaderSuffixes(const QStringList &suffixes)
     { m_headerSuffixes = suffixes; }
 
+    virtual bool isIndexing() const;
+
 Q_SIGNALS:
     void projectPathChanged(const QString &projectPath);
 
@@ -129,6 +131,8 @@ private Q_SLOTS:
     void onProjectAdded(ProjectExplorer::Project *project);
     void postEditorUpdate();
     void updateEditorSelections();
+    void onTaskStarted(const QString &type);
+    void onAllTasksFinished(const QString &type);
 
 private:
     QMap<QString, QString> buildWorkingCopyList();
@@ -175,10 +179,13 @@ private:
                       CppPreprocessor *preproc,
                       QStringList files);
 
+    void setIndexing(bool);
+
 private:
     Core::ICore *m_core;
     CPlusPlus::Snapshot m_snapshot;
 
+    bool m_indexing;
     // cache
     bool m_dirty;
     QStringList m_projectFiles;