The chief executive of leading Canadian oil producer Suncor Energy Inc. said on Tuesday that his company will increase output even if crude prices weaken further while vowing it will emerge stronger than ever from the current commodity industry downturn. The collapse in oil prices to the $30-a-barrel range has forced large oil producers in Canada and elsewhere to post losses and postpone new investments. But Suncor and its oil sands peers have plowed ahead with projects already under construction, which is…