Fix sweep command to use correct coordinate system

When reporting sweeps, it reported the location in the plane owner's
coordinate system instead of the player's.  Fortunately, they're the
same in normal usage.  They can differ only when a deity flies foreign
planes.

src/lib/subs/plnsub.c

@@ -943,7 +943,7 @@ plane_sweep(struct emp_qelem *plane_list, coord x, coord y)
 
 	if (chance((100.0 - pln_acc(pp)) / 100.0)) {
 	    pr("Sweep! in %s\n",
-	       xyas(sect.sct_x, sect.sct_y, pp->pln_own));
+	       xyas(sect.sct_x, sect.sct_y, player->cnum));
 	    mines_there--;
 	    found = 1;
 	}