The ornamental design for a cigarette lighter, as shown and described.
FIG. 1 is a perspective view of a cigarette lighter according to my new design;
FIG. 2 is a front view of the lighter of FIG. 1.
FIG. 3 is a right side view of the lighter of FIG. 1 (the left side view being a mirror image thereof);
FIG. 4 is a top view of the lighter of FIG. 1; and,
FIG. 5 is a bottom view of the lighter of FIG. 1.
The broken lines shown on the rear, front, and top surfaces of the lighter are included for the purpose of illustrating portions of the article and form no part of the claimed design.