Fix reflect.Pointer backward compatibility

Explanation of what this pull request does.
If we want to reflect.Pointer backward compatibility. here should use reflect.Ptr.

marshaler.go

@@ -732,7 +732,7 @@ func walkStruct(ctx encoderCtx, t *table, v reflect.Value) {
 			if fieldType.Anonymous {
 				if fieldType.Type.Kind() == reflect.Struct {
 					walkStruct(ctx, t, f)
-				} else if fieldType.Type.Kind() == reflect.Pointer && !f.IsNil() && f.Elem().Kind() == reflect.Struct {
+				} else if fieldType.Type.Kind() == reflect.Ptr && !f.IsNil() && f.Elem().Kind() == reflect.Struct {
 					walkStruct(ctx, t, f.Elem())
 				}
 				continue