patch 9.0.0481: in :def function all closures in loop get the same variables

Problem:    In a :def function all closures in a loop get the same variables.
Solution:   Use a separate list of variables for LOADOUTER and STOREOUTER.
            Not copied at end of loop yet.
diff --git a/src/proto/vim9cmds.pro b/src/proto/vim9cmds.pro
index 79a1557..a0c3ade 100644
--- a/src/proto/vim9cmds.pro
+++ b/src/proto/vim9cmds.pro
@@ -11,6 +11,8 @@
 char_u *compile_endfor(char_u *arg, cctx_T *cctx);
 char_u *compile_while(char_u *arg, cctx_T *cctx);
 char_u *compile_endwhile(char_u *arg, cctx_T *cctx);
+short get_loop_var_info(cctx_T *cctx, short *loop_var_idx);
+int get_loop_var_idx(cctx_T *cctx);
 char_u *compile_continue(char_u *arg, cctx_T *cctx);
 char_u *compile_break(char_u *arg, cctx_T *cctx);
 char_u *compile_block(char_u *arg, cctx_T *cctx);