Utils: Introduce GlobalFileChangeBlocker

Tracks application state, and signals when it is changed.

Supports forcing blocked state with reference counting.

Change-Id: Ic173d42446b1b08bd4a1e7c1acf38c68644d30b3
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/cpptools/cppbuiltinmodelmanagersupport.h

@@ -47,7 +47,6 @@ public:
     FollowSymbolInterface &followSymbolInterface() final;
     RefactoringEngineInterface &refactoringEngineInterface() final;
     std::unique_ptr<AbstractOverviewModel> createOverviewModel() final;
-    void setBackendJobsPostponed(bool) final {}
 
 private:
     QScopedPointer<CppCompletionAssistProvider> m_completionAssistProvider;

src/plugins/cpptools/cppmodelmanager.cpp

@@ -1318,11 +1318,6 @@ void CppModelManager::renameIncludes(const QString &oldFileName, const QString &
     }
 }
 
-void CppModelManager::setBackendJobsPostponed(bool postponed)
-{
-    d->m_activeModelManagerSupport->setBackendJobsPostponed(postponed);
-}
-
 void CppModelManager::onCoreAboutToClose()
 {
     Core::ProgressManager::cancelTasks(CppTools::Constants::TASK_INDEX);

src/plugins/cpptools/cppmodelmanager.h

@@ -230,8 +230,6 @@ public:
 
     void renameIncludes(const QString &oldFileName, const QString &newFileName);
 
-    void setBackendJobsPostponed(bool postponed);
-
 signals:
     /// Project data might be locked while this is emitted.
     void aboutToRemoveFiles(const QStringList &files);

src/plugins/cpptools/cppmodelmanagersupport.h

@@ -60,7 +60,6 @@ public:
     virtual FollowSymbolInterface &followSymbolInterface() = 0;
     virtual RefactoringEngineInterface &refactoringEngineInterface() = 0;
     virtual std::unique_ptr<AbstractOverviewModel> createOverviewModel() = 0;
-    virtual void setBackendJobsPostponed(bool yesno) = 0;
 };
 
 class CPPTOOLS_EXPORT ModelManagerSupportProvider