Julius Eastman was a shooting star of a composer. Born in 1940, Black and gay, he wrote his tender and shattering Second Symphony as a farewell to a former lover. The Philadelphia Orchestra, led by Dalia Stasevska, will perform Eastman’s work, along with John Williams’s jaunty Tuba Concerto, featuring Carol Jantsch. The Jan. 16-17 program closes with Mendelssohn’s Italian Symphony.