The ornamental design for a handdryer, as shown and described.
FIG. 1 is a front perspective view of the front, left, and top sides of a hand dryer showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a right side view thereof; and,
FIG. 5 is a top plan view thereof.
The broken lines and areas encircled by the broken lines shown represent unclaimed subject matter of the hand dryer and form no part of the claimed design.