The ornamental design for a jambliner, as shown and described.
FIG. 1 is a front perspective view of a jamb liner showing our new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a rear elevation view thereof;
FIG. 4 is a front elevation view thereof;
FIG. 5 is a top plan view thereof; and,
FIG. 6 is a bottom plan view thereof.
The drawings contain a symbolic break. The portion between the break lines forms no part of the claimed design. The broken lines as shown in FIGS. 1-4 depict boundary lines that form no part of the claimed design.