The ornamental design for a legging, as shown and described.
FIG. 1 is a perspective view of a legging shown in an environment;
FIG. 2 is a first side elevational view thereof;
FIG. 3 is an opposite side elevational view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a rear elevational view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines in FIGS. 1-7 represent portions of the footwear that form no part of the claimed design. The broken lines which define the bounds of the claimed design form no part thereof. The broken lines that form the footwear form no part of the claimed design.