Allow 'm' flag in rename flag position

The 'm' flag is used as a special flag by mixer-integration on the
client side to indicate a manifest record in the Manifest.MoM was
created by a local mix. Allow this flag and just set the rename flag to
renameUnset.

Signed-off-by: Matthew Johnson <matthew.johnson@intel.com>

swupd/files.go

@@ -192,6 +192,9 @@ func renameFromFlag(flag byte) (frename, error) {
 		return renameSet, nil
 	case '.':
 		return renameUnset, nil
+	case 'm':
+		// this is a special flag used by mixer-integration client-side
+		return renameUnset, nil
 	default:
 		return renameUnset, fmt.Errorf("invalid file rename flag: %v", flag)
 	}