They’re calling in reinforcements. Arguably the best sixth man in the league, J.R. Smith, and fellow guard Iman Shumpert are heading to the court of King James in a “blockbuster” trade. The struggling Knicks get forward Lance Thomas from Oklahoma City, along with two Cavs players. Promising youngster Dion Waiters will make his new home with the Thunder. For Cleveland, the swap is expected to free up LeBron on offense and boost the team’s perimeter defense — along with its shot at the title.