The ornamental design for a needleholder, as shown and described.
FIG. 1 is a bottom perspective view of a needle holder in accordance with the new design;
FIG. 2 is a left side perspective view thereof;
FIG. 3 is a right perspective view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a front, top perspective view thereof; and,
FIG. 7 is a rear, top perspective view thereof.
FIGS. 1-5 shown as broken in the middle and embraced with a bracket to indicate that no particular length is claimed. The broken line showing portions of a needle holder is included for the purpose of illustrating environmental structure and forms no part of the claimed design.