The ornamental design for a pencilsharpener, as shown and described.
FIG. 1 is a front elevational view of a pencil sharpener showing my new design; the rear elevational view being a mirror image of the front elevational view;
FIG. 2 is a left side view thereof; the right side view being a mirror image of the left side view;
FIG. 3 is a top plan view thereof; and,
FIG. 4 is a bottom plan view thereof.
The broken line showing portions of the pencil sharpener are included for information purposes only and form no part of the claimed design.