patch 8.2.1137: Vim9: modifiers not cleared after compiling function

Problem:    Vim9: modifiers not cleared after compiling function.
Solution:   Clear command modifiers. (closes #6396)
diff --git a/src/proto/ex_docmd.pro b/src/proto/ex_docmd.pro
index 8f5ac10..8505031 100644
--- a/src/proto/ex_docmd.pro
+++ b/src/proto/ex_docmd.pro
@@ -6,6 +6,7 @@
 void *getline_cookie(char_u *(*fgetline)(int, void *, int, int), void *cookie);
 char_u *getline_peek(char_u *(*fgetline)(int, void *, int, int), void *cookie);
 int parse_command_modifiers(exarg_T *eap, char **errormsg, int skip_only);
+void undo_cmdmod(exarg_T *eap, int save_msg_scroll);
 int parse_cmd_address(exarg_T *eap, char **errormsg, int silent);
 int checkforcmd(char_u **pp, char *cmd, int len);
 char_u *find_ex_command(exarg_T *eap, int *full, void *(*lookup)(char_u *, size_t, cctx_T *), cctx_T *cctx);