(Reuters) - Commodity miner and trader Glencore Plc reported a 9% fall in fourth-quarter copper production on Tuesday, as its Mutanda mine in the Democratic Republic of Congo suspended operations prematurely in November.The company, which has operations in over 150 countries, said copper output fell to 355,400 tonnes in the reported quarter and cobalt production dropped 13% to 11,900 tonnes.Glencore, which in December forecast a modest decline in copper output over the next three years, kept..