The ornamental design for a compressor, as shown and described.
FIG. 1 is a front elevation view of my design for a compressor;
FIG. 2 is a rear elevation view thereof;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is bottom view thereof; and,
FIG. 7 is an upper left front perspective view thereof.
The broken lines in FIGS. 1, 2, 3, and 5 are included for the purpose of illustrating portions of the compressor that form no part of the claimed design.