Before the 500-m men’s event at the Milano Speed Skating Stadium on Saturday, American Olympic champion Jordan Stolz , who won the 1000-m race here three nights ago, had a conversation with Bob Corby, his coach. Corby reminded Stolz that even if his start time in this sprint trailed his competition, the race would be won on the backstretch. “So you’ve got to burn, like you’ve never burned before,” Corby said. “And then everything will be fine.”  Stolz brought the required fire to the Olympic