The ornamental design for a lightfixture, as shown and described.
FIG. 1 is a perspective view showing our new design;
FIG. 2 is a side elevational view thereof;
FIG. 3 is a bottom plan view thereof; and,
FIG. 4 is a top plan view thereof.
The broken lines shown in the drawings are included for the purpose of illustrating portions of the light fixture that form no part of the claimed design.