The ornamental design for a headlamp, as shown and described.
FIG. 1 is a front left perspective view of a head lamp for a vehicle;
FIG. 2 is a front view thereof;
FIG. 3 is a top view thereof; and,
FIG. 4 is a front left perspective view thereof, mounted on a vehicle, with the rest of the vehicle shown in de-emphasized and half-tone portions so as to illustrate environmental structure. These portions form no part of the claimed design. More particularly, in FIG. 4, the head lamp is shown within the broken line, and the elements shown outside the broken line form no part of the claimed design, but are instead included to show environmental aspects thereof.
The broken lines shown in the drawings depict portions of the head lamp that form no part of the claimed design.