55 years ago tonight, Patsy Cline gave her final performance. Kansas City resident Mildred Keith took this photo minutes before Patsy went onstage and two days before the plane crash that claimed her life. The show that Patsy played was a benefit for radio DJ Cactus Jack McCall, who’d been killed in a car accident a month before. Dottie West, who was also on the bill for the benefit show, offered Patsy a ride back to Nashville but she turned her down, saying, “Don’t worry about me, Hoss…