JOHANNESBURG, South Africa — Zimbabwe’s ruling party will not tolerate an opposition victory at elections this weekend, Robert Mugabe has signalled. At a rally in the capital Harare, the president said that the Movement for Democratic Change’s leader, Morgan Tsvangirai, would “never, never rule this country.” Mr. Mugabe told the crowd, many of whom had been brought in from the rural areas where his support is strongest: “Those who want to vote for him can do so but those votes will be wasted votes.”