patch 8.1.1583: set_ref_in_list() only sets ref in items

Problem:    Set_ref_in_list() only sets ref in items.
Solution:   Rename to set_ref_in_list_items() to avoid confusion.
diff --git a/src/popupwin.c b/src/popupwin.c
index d675a44..f6da71d 100644
--- a/src/popupwin.c
+++ b/src/popupwin.c
@@ -2297,11 +2297,7 @@
 	tv.vval.v_partial = wp->w_filter_cb.cb_partial;
 	abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
     }
-    if (wp->w_popup_mask != NULL && wp->w_popup_mask->lv_copyID != copyID)
-    {
-	wp->w_popup_mask->lv_copyID = copyID;
-	abort = abort || set_ref_in_list(wp->w_popup_mask, copyID, NULL);
-    }
+    abort = abort || set_ref_in_list(wp->w_popup_mask, copyID);
     return abort;
 }