It may be ironic that the biggest discovery in a concert dominated by new music was a work that is nearly 350 years old. Jean-Baptiste Lully’s music from “Le Bourgeois gentilhomme,” performed by Louis Langrée and the Cincinnati Symphony Orchestra, has never sounded so fresh as it did, played just before David Lang’s massive, percussive score of 2013, “man made.” But perhaps that was the point.