QMakePM: Fix crash when running qmake before the project is parsed

Disable the build actions properly.

Change-Id: Id4e2906b1891fcb3387e23cb0e0a8c1f119d2426
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/qmakeprojectmanager/qmakeprojectmanagerplugin.h

@@ -65,6 +65,7 @@ private slots:
 private:
     void projectChanged();
     void activeTargetChanged();
+    void updateActions();
     void updateRunQMakeAction();
     void updateContextActions();
     void buildStateChanged(ProjectExplorer::Project *pro);