The ornamental design for a bagholder, as shown and described.
FIG. 1 is a perspective view of a bag holder showing my new design;
FIG. 2 is a top view of the bag holder of FIG. 1;
FIG. 3 is a bottom view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a left side elevational view thereof; and,
FIG. 6 is a right side elevational view thereof.
The ornamental design which is claimed is shown in solid lines in the drawings. Any broken lines in the drawings are for illustrative purposes only and form no part of the claimed design.