TORONTO - Anti-Semitism is an intractable evil that all Canadians, especially elected leaders, ''must stand up'' and confront, Brian Mulroney said last night. He denounced the pro-Hitler stance of William Lyon Mackenzie King, the prime minister of the time, as contributing to the deaths of "countless Jews." In a speech that launched a two-day conference probing the scope of anti-Semitism, Mr. Mulroney said that hatred toward Jews -- a philosophy ''born in ignorance and nurtured in envy'' -- continues to be a scourge in Canada. Addressing an audience at the University of Toronto, Mr. Mulroney also accused anti-Semites of broadening...