patch 8.2.0585: Vim9: # comment not recognized after :vim9script

Problem:    Vim9: # comment not recognized after :vim9script.
Solution:   Check script type. Make comment after ":echo" work.  And in
            several other places.
diff --git a/src/proto/ex_docmd.pro b/src/proto/ex_docmd.pro
index af70e2d..eba5ee4 100644
--- a/src/proto/ex_docmd.pro
+++ b/src/proto/ex_docmd.pro
@@ -19,6 +19,7 @@
 char_u *skip_cmd_arg(char_u *p, int rembs);
 int get_bad_opt(char_u *p, exarg_T *eap);
 int ends_excmd(int c);
+int ends_excmd2(char_u *before, char_u *cmd);
 char_u *find_nextcmd(char_u *p);
 char_u *check_nextcmd(char_u *p);
 char_u *get_command_name(expand_T *xp, int idx);