patch 9.1.1232: Vim script is missing the tuple data type

Problem:  Vim script is missing the tuple data type
Solution: Add support for the tuple data type
          (Yegappan Lakshmanan)

closes: #16776

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/list.pro b/src/proto/list.pro
index 27bea5e..cb05203 100644
--- a/src/proto/list.pro
+++ b/src/proto/list.pro
@@ -50,6 +50,8 @@
 int write_list(FILE *fd, list_T *list, int binary);
 void init_static_list(staticList10_T *sl);
 void f_list2str(typval_T *argvars, typval_T *rettv);
+void f_list2tuple(typval_T *argvars, typval_T *rettv);
+void f_tuple2list(typval_T *argvars, typval_T *rettv);
 void f_sort(typval_T *argvars, typval_T *rettv);
 void f_uniq(typval_T *argvars, typval_T *rettv);
 int filter_map_one(typval_T *tv, typval_T *expr, filtermap_T filtermap, funccall_T *fc, typval_T *newtv, int *remp);