* OPEC leaves 2014, 2015 demand forecasts steady * Report says winter demand should support crude market * Saudi is looking to defend market share - PIRA * OPEC delegate says Saudi Arabia should cut its output (Adds further details on Saudi output, comment from PIRA) By Alex Lawler LONDON, Oct 10 (Reuters) - Top oil exporter Saudi Arabia told OPEC it raised its oil production in September by 100,000 barrels per day, adding to signs it has yet to respond to a drop in prices well below $100 a barrel by trimming output. ...