The Miami Heat on their final day at the NBA Las Vegas Summer League altered their prospective training camp roster Saturday by releasing two-way-contract players Mychal Mulder and Javonte Smart. In their places, the Heat signed defensive-minded guard Marcus Garrett to a two-way contract for the second consecutive summer and also added forward Darius Days, who has been playing on the San Antonio Spurs’ summer roster. The moves keep the Heat offseason roster at 18 players, two below the league maximum, with an anticipated return by veeran power forward Udonis Haslem expected to bring the total to 19. Mulder and Smart were waived within hours of starting the Heat’s Friday night summer-league loss to the Toronto Raptors. Mulder closed that loss 2 of 8 from the field and 1 of 6 on 3-pointers, having struggled throughout summer league with his trademark 3-point shooting. Signed to a Heat two-way contract on March 24, Mulder appeared in two games with the Heat last season, averaging 7.0 points, 1.5 rebounds, 1.0 assists in 22.1 minutes per appearance. Smart closed Friday night’s loss 4 of 13 from the field with six turnovers, failing to provide efficient scoring in summer league as an undersized shooting guard, and unable to provide playmaking. Signed to his two-way contract on Feb.