The ornamental design for an exitlightbulb, as shown and described.
FIG. 1 is a plan view of the exit light bulb of the present invention; FIG.
2 is a side plan view of the exit light bulb of FIG. 1; FIG. 3 is an end
view showing the screw shell end of the exit light bulb of FIG. 1., as
seen from the top of FIG. 1; and, FIG. 4 is an end view of the exit light
bulb of FIG. 1, as seen from the bottom of FIG. 1.