patch 8.2.4260: Vim9: can still use a global function without g:

Problem:    Vim9: can still use a global function without g: at the script
            level.
Solution:   Also check for g: at the script level. (issue #9637)
diff --git a/src/proto/userfunc.pro b/src/proto/userfunc.pro
index 464d7f2..4e30d83 100644
--- a/src/proto/userfunc.pro
+++ b/src/proto/userfunc.pro
@@ -11,6 +11,7 @@
 ufunc_T *find_func_even_dead(char_u *name, int flags);
 ufunc_T *find_func(char_u *name, int is_global);
 int func_is_global(ufunc_T *ufunc);
+int func_requires_g_prefix(ufunc_T *ufunc);
 int func_name_refcount(char_u *name);
 void func_clear_free(ufunc_T *fp, int force);
 int copy_func(char_u *lambda, char_u *global, ectx_T *ectx);