The ornamental design for a pencilsharpener, as shown and described.
FIG. 1 is a perspective view of a pencil sharpener showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left view thereof;
FIG. 5 is a right view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is another perspective view thereof.
The broken lines on the top in FIG. 6 and on the bottom in FIG. 7 are included to show portions of the pencil sharpener that form no part of the claimed design.