The ornamental design for a hinge connector, as shown and described.
FIG. 1 is a perspective view of the hinge connector;
FIG. 2 is an end view thereof, the other end view being a mirror image;
FIG. 3 is a front side view thereof;
FIG. 4 is a rear side view thereof;
FIG. 5 is a top view thereof; and,
FIG. 6 is a bottom view thereof.
The design is shown fragmented in FIGS. 1, 3, 4, 5, and 6 in order to indicate that a specific length and width of the hinge connector form no part of the claimed design.