The ornamental design for a rollingstock, as shown and described.
FIG. 1 is a perspective view of a rolling stock bearing the design.
FIG. 2 is a front elevation view of the rolling stock. A rear elevation view of the rolling stock appears identical to the front elevation view.
FIG. 3 is a left side elevation view of the rolling stock. A right side elevation view of the rolling stock appears identical to the left side elevation view; and,
FIG. 4 is a top plan view of the rolling stock.
The broken lines shown in the drawings illustrate portions of the rolling stock that form no part of the claimed design. The bottom view forms no part of the claimed design.