‘I’m Still Standing,’” Mitchell said to the crowd. “But I think I have to sing, ‘I’m still sitting after all these years.’” As if that weren’t enough, Brandi Carlile, Annie Lennox and Meryl Streep — yes, Meryl Streep — also joined in the fun for an all-star rendition of “I’m Still Standing” that drew cheers from the crowd of 17,000 at the amphitheater.It was a joyous highlight of Mitchell’s two-night stand at the Hollywood Bowl — her first headlining concerts in Los Angeles in 24 years.