ZIMBABWE: President Emmerson Mnangagwa has signed into law constitutional amendments that abolish direct presidential elections, postpone the next vote and extend his tenure, despite strong opposition from critics.Mr Mnangagwa, aged 83, had previously pledged to step down when his second and final term ends in 2028.The revised constitution makes MPs responsible for choosing the president and extends their terms of office and that of the president from five years to seven.