(Reuters) - Global auto sales for Japanese carmakers halved in April as the coronavirus pandemic forced governments to impose lockdowns that left streets empty and showrooms deserted.Japan's top eight automakers together posted a decline of 50.1% in April sales, according to a Reuters calculation. Toyota Motor's worldwide sales including units Daihatsu and Hino fell 45% to 472,703 vehicles - the fourth straight month of declines. Toyota's performance was dragged down by a 51% slump in sales..