Another of Showtime’s documentaries, this one, made in 2012 but premiering tonight, is a profile of one of the wildest, most talented and most unpredictable drummers of the past 50 years. No, it’s not a film about Keith Moon. But it’s one about Ginger Baker, the drummer who could fill an entire side of a live Cream album with an extended solo – and whose personality, drives and interests off the stage and outside the studio were just as driven.