Kool G Rap’s “Men at Work” concluded The Roots’ Sunday evening set in Brooklyn’s Prospect Park. In the swelter, a paunchy Black Thought perspired through the rap standard while his legendary crew capered Pip-like in the background. A master of breath control, Black Thought expelled not a pant and it was an exhausting exercise. The Roots are serious showmen and I can’t say that I wasn’t entertained but going to a hip hop concert and hearing that repeated declamation “Men at Work” prickled as a reminder that for too many “Men at Work” remains hip hop’s definition.