Add comment about fShutdown in RPC thread.
Add comment about fShutdown in RPC thread.

wiggi/huntercoin,domob1812/huntercoin,chronokings/huntercoin,fsb4000/huntercoin,domob1812/huntercoin,wiggi/huntercoin,fsb4000/huntercoin,fsb4000/huntercoin,wiggi/huntercoin,fsb4000/huntercoin,chronokings/huntercoin,domob1812/huntercoin,chronokings/huntercoin,domob1812/huntercoin,wiggi/huntercoin,chronokings/huntercoin