Revert "Debugger: Fix write error on terminated GDB process"

This reverts commit 87c00b86db.

Reason for revert: Breaks shutting down the cdbengine and according to the diagram in debuggerplugin.cpp this is an expected transition.

Change-Id: I051ccd315dffcadf60892c33cd7c1f3523b2f8e0
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/debugger/debuggerengine.cpp

@@ -380,10 +380,6 @@ public:
     void doShutdownEngine()
     {
         m_engine->setState(EngineShutdownRequested);
-        if (m_engine->isDying()) {
-            m_engine->notifyEngineShutdownFinished();
-            return;
-        }
         m_engine->startDying();
         m_engine->showMessage("CALL: SHUTDOWN ENGINE");
         m_engine->shutdownEngine();