patch 9.1.0690: cannot set special highlight kind in popupmenu

Problem:  cannot set special highlight kind in popupmenu
Solution: add kind_hlgroup item to complete function
          (glepnir)

closes: #15561

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/structs.h b/src/structs.h
index 847972f..79f415d 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -4475,6 +4475,7 @@
     int		pum_score;	  // fuzzy match score
     int		pum_idx;	  // index of item before sorting by score
     int		pum_user_hlattr;  // highlight attribute to combine with
+    int		pum_user_kind_hlattr; // highlight attribute for kind
 } pumitem_T;
 
 /*