The ornamental design for a postlightfixture, as shown and described.
FIG. 1 is a front elevational view of a post light fixture embodying our
new design, wherein the right, left, and rear elevational views are
identical thereto, and the broken lines are for illustrative purposes only
and form no part of the claimed design; and
FIG. 2 is a top plan view thereof the bottom of the fixture is hidden in
use and wholly functional.