Judging by the Nuremburg Trials, he likely would have been executed almost without question. There would have had a trial but we all know what the verdict would have been. The bigger question probably is whether he would have lived to see the actual trial. I'm pretty sure whoever captured him would have protected him once higher brass got involved, but if you were the average GI or Soviet infantryman and you somehow stumbled upon Adolf Hitler somewhere, there is a good chance you would have just shot him to instantly become world famous.