Gary Nagle is discreet, but determined to transform Glencore. Two-and-a-half years after his arrival at the helm of the commodities trading behemoth, the 48-year-old South African is quietly continuing the task started by his predecessor and compatriot Ivan Glasenberg (who tapped him for the job): turning the oil and mining trader, which has been listed on the London Stock Exchange since 2010, into a “normal” company.That task is far from