OSLO (Reuters) - Swedish oil firm Lundin Petroleum , a partner in Norway's giant Sverdrup oilfield, posted a smaller-than-expected decline in third-quarter earnings on Thursday, while raising output forecasts and cutting capital spending guidance.Earnings before interest, tax, depreciation and amortisation (EBITDA) fell to $411 million (£317.5 million) in the third quarter from $504 million a year earlier as crude prices declined, beating a mean estimate of $378 million in a Refinitiv poll.The..