Agence France-Presse: The devastating Gulf of Mexico oil spill is set to cost BP a staggering 40 billion dollars, the British energy giant revealed on Tuesday, after ramping up its estimate by almost a quarter. But the British oil giant also reported a net profit of 1.785 billion dollars for the third quarter in contrast to a loss of 16.9 billion dollars during the second quarter of this year, a huge turnaround. BP said it had taken an additional third quarter charge of 7.7 billion dollars, taking the company’s…