patch 8.2.4573: a nested function is compiled for debugging without context

Problem:    A nested function (closure) is compiled for debugging without
            context.
Solution:   Check if a nested function is marked for debugging before
            compiling it.  Give an error when trying to compile a closure
            without its context. (closes #9951)
diff --git a/src/proto/vim9execute.pro b/src/proto/vim9execute.pro
index 6f42fc8..bd67092 100644
--- a/src/proto/vim9execute.pro
+++ b/src/proto/vim9execute.pro
@@ -1,5 +1,6 @@
 /* vim9execute.c */
 void to_string_error(vartype_T vartype);
+void update_has_breakpoint(ufunc_T *ufunc);
 void funcstack_check_refcount(funcstack_T *funcstack);
 int set_ref_in_funcstacks(int copyID);
 char_u *char_from_string(char_u *str, varnumber_T index);