THERE WAS A BEVY OF A-LISTER friends there to crank up the fun —Christina Applegate, Neil Young, Steve Earle, Jack Black and Brad Pitt to name a few — but for Stephen Stills, the third annual Light Up the Blues benefit concert made for a poignant evening. The event, which raises funds for autism research, launched in honor of Stills’ 18-year-old son Henry, who has Asperger’s syndrome. “[Neil and Stephen] are two of my heroes,” said Earle, who turned to Stills for guidance when his own son, John Henry, now 5, was diagnosed with autism in 2012. After dropping $23,000 on a Fender guitar signed by the performers, Pitt introduced a set by Young and Stills, joking, “Without those guys, a lot of us would’ve had better grades in high…
