FIG. 1 is a perspective view of a compressor embodying the ornamental design of the present invention. FIG. 2 is a front view thereof. FIG. 3 is a rear view thereof. FIG. 4 is a side view thereof. FIG. 5 is an opposite side thereof. FIG. 6 is a top view thereof; and, FIG. 7 is a bottom view thereof. The broken lines in the figures are for illustrative purposes only and form no part of the claimed design.