ATLANTA — Georgia Tech received a late boost with the signing of running back Myles Autry. Coach Paul Johnson said that Autry, whose brother Anthony is a receiver with the Yellow Jackets, is one of six newcomers who have a chance to fill a variety of roles in summer camp. Georgia Tech signed 21 players to national letters of intent Wednesday — six offensive linemen, four defensive backs, three defensive ends, three linebackers, two running backs, two receivers and one quarterback.