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/marionette/main.cpp

@@ -184,9 +184,7 @@ void MarionetteThread::main(MarionetteThread& self)
 			if (sendExceptionInd)
 			{
 				mrntt::exitCode = EXIT_FAILURE;
-				mrntt::mrntt.finalizeReq({nullptr, std::bind(
-					&mrntt::marionetteFinalizeReqCb,
-					std::placeholders::_1)});
+				mrntt::mrntt.exceptionInd();
 			}
         }