ProjectExplorer/Debugger: Add a 'Run as root' option for Unix hosts

For local run and GDB debug, with or without terminal.

Task-number: QTCREATORBUG-2831
Task-number: QTCREATORBUG-25330
Change-Id: I9b5d2156bcffea4f358474ecdbcad580a4419917
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/debugger/terminal.h

@@ -78,6 +78,7 @@ public:
     qint64 applicationMainThreadId() const { return m_applicationMainThreadId; }
 
     void interruptProcess();
+    void setRunAsRoot(bool on);
 
 private:
     void start() final;
@@ -90,6 +91,7 @@ private:
     ProjectExplorer::Runnable m_stubRunnable;
     qint64 m_applicationPid = 0;
     qint64 m_applicationMainThreadId = 0;
+    bool m_runAsRoot = false;
 };
 
 } // namespace Internal