Mrntt: Re-add exceptionInd

This now ensures that finalizeReq is indeed called from mrntt,
since exception-experiencing threads will post an exceptionInd
to mrntt, which will then call finalizeReq.

smocore/include/marionette/marionette.h

@@ -23,9 +23,12 @@ public:
 	typedef std::function<void(bool)> mrnttLifetimeMgmtOpCbFn;
 	void initializeReq(Callback<mrnttLifetimeMgmtOpCbFn> callback);
 	void finalizeReq(Callback<mrnttLifetimeMgmtOpCbFn> callback);
+	// Intentionally doesn't take a callback.
+	void exceptionInd();
 
 private:
 	class MrnttLifetimeMgmtOp;
+	class TerminationEvent;
 };
 
 extern std::atomic<int> exitCode;