The ornamental design for a garmenthanger, as shown and described.
FIG. 1 is a front perspective view of a garment hanger in accordance with the present design;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a right-side view thereof;
FIG. 5 is a rear view thereof;
FIG. 6 is a left-side view thereof; and,
FIG. 7 is a bottom view thereof.
The broken lines shown in the drawings represent unclaimed subject matter and form no part of the claimed design. The claimed design is not limited to the gray color shown in the drawings.