Wel, the expression portmanteau word comes from Through the Looking Glass ("Well slithy means ...You see it's like a portmanteau - there are two meanings packed up into one word.")

But whinging is probably more recent - Aussies use it a fair amount, especially in the expression "Whinging Pom". So it's not complimentary. It means very much the same as "griping", which I thought was another portmantaeu made up of grousing and sniping. But in fact it turns out it is from the Old English gripen, and goes back even further.