TOKYO—Races often end in a blur for Canada’s Maggie MacNeil, who wears glasses outside the pool but doesn’t use contacts or prescription goggles when swimming. That means it takes a second or two for the picture to become clear after she’s touched the wall as she tries to focus in on the results board. Did I win? That killer suspense was there at the Tokyo Olympics on Monday. MacNeil made the turn nearly last—in seventh place—in the 100-meter butterfly final, then put in a huge second lap. “I was just trying to squint and see where I came,” she said. “I heard my name getting called so I knew I must have done something good.” On realizing she’d won her first Olympic gold, MacNeil mouthed “oh my God” and got a big hug from defending champion Sarah Sjoestroem. It was a frenetic 24-hours for MacNeil. The 21-year-old from London, Ontario …