The ornamental design for a lightfixture, as shown and described.
FIG. 1 is a perspective view of the light fixture embodying my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is a left side view thereof;
FIG. 7 is a right side view thereof.
The broken line showing of the switch and mounting structure is for the purpose of illustrating portions of the light fixture and forms no part of the claimed design.