patch 9.0.0331: cannot use items() on a string
Problem: Cannot use items() on a string.
Solution: Make items() work on a string. (closes #11016)
diff --git a/src/proto/list.pro b/src/proto/list.pro
index 611aeac..6c3523a 100644
--- a/src/proto/list.pro
+++ b/src/proto/list.pro
@@ -36,6 +36,7 @@
void f_flatten(typval_T *argvars, typval_T *rettv);
void f_flattennew(typval_T *argvars, typval_T *rettv);
void list2items(typval_T *argvars, typval_T *rettv);
+void string2items(typval_T *argvars, typval_T *rettv);
int list_extend(list_T *l1, list_T *l2, listitem_T *bef);
int list_concat(list_T *l1, list_T *l2, typval_T *tv);
list_T *list_slice(list_T *ol, long n1, long n2);