To cop a song title from the band to which he’ll be forever linked, Michael Cohl is . . . happy. With the Rolling Stones on a record-shattering run with their Bigger Bang world tour, as well as hot tours by Barbra Streisand and the Who under his direction, it is easy to see why Cohl’s spirits are high. But the legendary promoter is not one to kick back, relax and watch the waves of people roll in. Indeed, Cohl may or may not do an interview on the front end of a tour or after it wraps, but he is generally off-limits come showtime.