South Africa’s scandal-ridden president said Sunday the ruling party has made “mistakes” and is determined to root out the corruption that is destroying the country’s democracy, as a shaken African National Congress begins looking for a new leader before the next election in 2019. President Jacob Zuma tried to rally the ANC at its 105th anniversary celebration after a year in which the party saw its worst election showing since taking power a generation ago at the end of white minority rule.