The ornamental design for a matchstriker, as shown and described.
FIG. 1 is a perspective view of a match striker showing my new design.
FIG. 2 is a side view thereof.
FIG. 3 is a top view thereof; and,
FIG. 4 is a bottom view thereof.
The broken lines shown in the drawings depict portions of the match striker that form no part of the claimed design; in FIGS. 1-4, matches are shown in broken lines and form no part of the design.