By Tzvi Machlin Never let it be said that San Francisco 49ers head coach Kyle Shanahan doesn’t have a good sense of humor. Speaking to the media on Friday following the team’s acquisition star running back Christian McCaffrey, Shanahan was asked about the team passing on him in the 2017 NFL Draft. His response was priceless. “I told Christian this was our plan all along. We wanted to build a D-line first and then add him five-and-a-half years later,” Shanahan joked. Shanahan and the 49ers infamously took defensive end Solomon Thomas with the No. 3 overall pick in that draft. McCaffrey went to …