Paul McCartney, Ringo Starr, and Yoko Ono are leading tributes to John Lennon on the 40th anniversary of his death.The late Beatles star was shot dead by Mark David Chapman outside his Dakota apartment building home in New York on December 8, 1980, and his wife and former bandmates were among those marking the sad date in music history on Tuesday.Paying tribute to his old pal on Twitter, McCartney shared a photo of the pair sitting together in a recording studio prior to Lennon’s death, and