ProjectExplorer: Remove unused variable

Change-Id: Ibaee479a6f5442d5b465f2b2c3c5c55352005014
Reviewed-by: hjk <hjk@qt.io>

src/plugins/projectexplorer/appoutputpane.h

@@ -138,7 +138,6 @@ private:
 
     TabWidget *m_tabWidget;
     QVector<RunControlTab> m_runControlTabs;
-    int m_runControlCount = 0;
     QAction *m_stopAction;
     QAction *m_closeCurrentTabAction;
     QAction *m_closeAllTabsAction;