“Povo no Poder,” or “People in Power,” by the rap star Azagaia, has become the unofficial anthem of the protests over a disputed election. By Tavares Cebola and John Eligon Tavares Cebola reported from Marracuene, Mozambique, and John Eligon from Johannesburg. The young men huddled around a parked car, bobbing to a beat that thumped…