The ornamental design for a buildingpanel, as shown and described.
FIG. 1 is a front perspective view of a building panel showing our new design.
FIG. 2 is a rear perspective view thereof.
FIG. 3 is another front perspective view of a building panel showing our new design.
FIG. 4 is a front view thereof.
FIG. 5 is a rear view thereof.
FIG. 6 is a left side view thereof.
FIG. 7 is a right side view thereof; and,
FIG. 8 is a top plan view thereof.
The broken lines in the figures are for the purpose of illustrating environmental structure and form no part of the claimed design. The oblique shade lines show transparency and not surface ornamentation.