RIYADH, Saudi Arabia — Canelo Alvarez regained the WBC super middleweight championship on Saturday night, using precise counterpunching and a strong second-half performance to defeat Christian Mbilli by unanimous decision. The judges scored the fight 115-112, 116-111 and 117-110 for Alvarez, who handed Mbilli his first professional defeat. Alvarez improved to 64-3-2, while Mbilli fell