The ornamental design of the furniture support, as shown and described.
FIG. 1 is a perspective view of a furniture support;
FIG. 2 is a left side elevational view, the right side being a mirror image thereof;
FIG. 3 is a front elevational view, the rear being a mirror image thereof; and,
FIG. 4 is a top view, the bottom being a mirror image thereof.
The broken line showing of a triangular structure at the top and bottom of the support structure illustrates the environment of the support structure; is for illustrative purposes only; and forms no part of the claimed design.