Remove backend dependency from fs/hash

cmd/dbhashsum/dbhashsum.go

@@ -4,7 +4,9 @@ import (
 	"context"
 	"os"
 
+	"github.com/rclone/rclone/backend/dropbox/dbhash"
 	"github.com/rclone/rclone/cmd"
+	"github.com/rclone/rclone/fs/hash"
 	"github.com/rclone/rclone/fs/operations"
 	"github.com/spf13/cobra"
 )
@@ -26,7 +28,8 @@ The output is in the same format as md5sum and sha1sum.
 		cmd.CheckArgs(1, 1, command, args)
 		fsrc := cmd.NewFsSrc(args)
 		cmd.Run(false, false, command, func() error {
-			return operations.DropboxHashSum(context.Background(), fsrc, os.Stdout)
+			dbHashType := hash.RegisterHash("Dropbox", 64, dbhash.New)
+			return operations.HashLister(context.Background(), dbHashType, fsrc, os.Stdout)
 		})
 	},
 }

cmd/hashsum/hashsum.go

@@ -41,7 +41,7 @@ Then
 		cmd.CheckArgs(0, 2, command, args)
 		if len(args) == 0 {
 			fmt.Printf("Supported hashes are:\n")
-			for _, ht := range hash.Supported.Array() {
+			for _, ht := range hash.Supported().Array() {
 				fmt.Printf("  * %v\n", ht)
 			}
 			return nil