ANTHONY BOADLE A third senator has died of COVID-19 in Brazil, raising questions around precautions taken in the country's Congress where as many as one-in-three lawmakers has been infected with the virus devastating Latin America's largest nation. Senator Major Olimpio, a former policeman who backed and later fell out with far-right President Jair Bolsonaro, was declared brain dead on Thursday by doctors at a Sao Paulo hospital where he had been in intensive care for three weeks. The two oldest senators in Congress, aged 87 and 83, also succumbed to COVID-19. But the death of Olimpio, just 58 and the…