patch 8.2.2533: Vim9: cannot use a range with :unlet

Problem:    Vim9: cannot use a range with :unlet.
Solution:   Implement ISN_UNLETRANGE.
diff --git a/src/proto/evalvars.pro b/src/proto/evalvars.pro
index 144dc7c..cf4db0b 100644
--- a/src/proto/evalvars.pro
+++ b/src/proto/evalvars.pro
@@ -23,6 +23,7 @@
 void ex_unlet(exarg_T *eap);
 void ex_lockvar(exarg_T *eap);
 void ex_unletlock(exarg_T *eap, char_u *argstart, int deep, int glv_flags, int (*callback)(lval_T *, char_u *, exarg_T *, int, void *), void *cookie);
+int list_unlet_range(list_T *l, listitem_T *li_first, char_u *name, long n1_arg, int has_n2, long n2);
 int do_unlet(char_u *name, int forceit);
 void item_lock(typval_T *tv, int deep, int lock, int check_refcount);
 void del_menutrans_vars(void);
diff --git a/src/proto/list.pro b/src/proto/list.pro
index 4ccc897..192981d 100644
--- a/src/proto/list.pro
+++ b/src/proto/list.pro
@@ -20,6 +20,7 @@
 listitem_T *list_find(list_T *l, long n);
 long list_find_nr(list_T *l, long idx, int *errorp);
 char_u *list_find_str(list_T *l, long idx);
+listitem_T *list_find_index(list_T *l, long *idx);
 long list_idx_of_item(list_T *l, listitem_T *item);
 void list_append(list_T *l, listitem_T *item);
 int list_append_tv(list_T *l, typval_T *tv);