Somewhere, somehow, Charlie Watts is wryly smiling down at us (in his finest Savile Row suit, of course) as we listen to “Troubles A’ Coming,” a previously unheard Rolling Stones song that took four damn decades to get released. Recorded in 1979 for the Tattoo You sessions, the track is actually a Chi-Lites cover — just with way more electric guitars and Watts swingin’ the hell out of his drum kit. This, and other rarities, will appear on the band’s upcoming Tattoo You reissue. “Charlie was the heartbeat for the band and also a very steady personality,” Mick Jagger explained on The Howard Stern Show yesterday. “He was not to be perturbed. He was a very reliable person, wasn’t a diva — that’s the last thing you want in a drummer.” And, according to the lore, if you dared to be a diva to Watts, it wasn’t going to end well.