CDB: Fix missing session cleanup on inferior exit, new state model

Adapt to new state model, make sure session is always cleaned
when invoked from processExited event handler, remove calls
to DebuggerManager::notifyXX().

src/plugins/debugger/cdb/cdbdebugengine.h

@@ -114,6 +114,7 @@ private slots:
     void warning(const QString &w);
 
 private:
+    void setState(DebuggerState state, const char *func, int line);
     bool startAttachDebugger(qint64 pid, DebuggerStartMode sm, QString *errorMessage);
     bool startDebuggerWithExecutable(DebuggerStartMode sm, QString *errorMessage);
     void startWatchTimer();