New York City’s “Homecoming” concert at Central Park was abruptly halted in the middle of Barry Manilow’s performance Saturday evening — as lightning storms tied to approaching Hurricane Henri descended on the Big Apple. Concertgoers were told at 7:37 p.m. to “proceed to your vehicles and protected areas outside of the event center” as Manilow was singing his 1978 hit “Can’t Smile Without You.”