SPARTANBURG, S.C. — Sam Darnold has not been in a true quarterback competition since the summer of 2016. The then-18-year-old Southern Cal kid battled a Trojan quarterback room of future NFL QB Cody Kessler and his blue-chip backups, Max Browne and Ricky Town. Darnold and the rest of the Carolina Panthers arrived at Wofford College on Tuesday to report for training camp, which starts Wednesday morning. Darnold said there are lessons from 2016 that he’ll lean on. “I was in a quarterback competition in college. … (Kessler) ended up winning the job, and then I ended up stepping in, I think the …