The ornamental design for a compressor, as shown and described.
FIG. 1 is a front- perspective view of a compressor showing my new design;
FIG. 2 is a rear perspective view;
FIG. 3 is a top plan view;
FIG. 4 is a right side elevational view;
FIG. 5 is a rear elevational view;
FIG. 6 is a left side elevational view; and,
FIG. 7 is a front elevational view.
In each of FIGS. 4 through 7, the broken lines illustrating other portions of the earphone are for illustrative purposes only, and form no part of the claimed design.