HOUSTON — George Springer wasn’t quite sure if his towering fly ball was going to have enough distance. Three feet shorter or to the right, and it might be an game-ending fly out. Instead, Springer’s shot narrowly crossed the yellow line for a game-winning three-run homer in the 13th inning, capping a five-RBI game and lifting the Houston Astros to a 5-3 victory over the Seattle Mariners on Wednesday night.“I knew I had hit it OK. I was just glad it went over the line,” Springer said. Springer’s shot off Chase De Jong (0-1), who started the inning to make his major-league debut, landed in the farthest seat of the first row of the left-field Crawford Boxes.Evan Gattis drew a one-out walk and advanced to second on Norichika Aoki’s single with two outs, setting the stage for Springer’s big hit.