Debugger: Make DebuggerEngine internal

Expose less of debugger internals to the device plugins.

Change-Id: Ie78756b033fae3fe02bff92eadf26b7319990605
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>
Reviewed-by: hjk <hjk121@nokiamail.com>

src/plugins/android/androiddebugsupport.h

@@ -33,10 +33,7 @@
 
 #include "androidrunconfiguration.h"
 
-namespace Debugger {
-class DebuggerEngine;
-class DebuggerRunControl;
-}
+namespace Debugger { class DebuggerRunControl; }
 
 namespace ProjectExplorer { class RunControl; }
 
@@ -60,7 +57,6 @@ public:
 private:
     void handleRemoteProcessStarted(int gdbServerPort, int qmlPort);
 
-    Debugger::DebuggerEngine *m_engine;
     Debugger::DebuggerRunControl *m_runControl;
     AndroidRunner * const m_runner;
 };