The ornamental design for a headlamp as shown and described.
FIG. 1 is isometric frontal view in perspective of a motor vehicle that includes headlamp;
FIG. 2 is a top view of the headlamp of FIG. 1;
FIG. 3 is a front view of the headlamp of FIG. 1;
FIG. 4 is a side view of the headlamp of FIG. 1; and,
FIG. 5 is a rear view of the headlamp of FIG. 1.
This design is not limited to the exact details shown in the Drawings, since equivalents and colorable imitations thereof will be evident to a person of ordinary skill in the art. Broken lines are used in the Drawings to denote certain subject matter, for example, environmental structure or boundaries, that form no part of the design to be patented. Thus, within the scope of the appended claim, which is intended to cover only the ornamental and novel elements shown in the Drawings, the invention may be practiced otherwise than as specifically shown and described herein.