Some global variables can be accessed from ractors

Some global variables should be used from non-main Ractors.
[Bug #17268]

```ruby
     # ractor-local (derived from created ractor): debug
     '$DEBUG' => $DEBUG,
     '$-d' => $-d,

     # ractor-local (derived from created ractor): verbose
     '$VERBOSE' => $VERBOSE,
     '$-w' => $-w,
     '$-W' => $-W,
     '$-v' => $-v,

     # process-local (readonly): other commandline parameters
     '$-p' => $-p,
     '$-l' => $-l,
     '$-a' => $-a,

     # process-local (readonly): getpid
     '$$'  => $$,

     # thread local: process result
     '$?'  => $?,

     # scope local: match
     '$~'  => $~.inspect,
     '$&'  => $&,
     '$`'  => $`,
     '$\''  => $',
     '$+'  => $+,
     '$1'  => $1,

     # scope local: last line
     '$_' => $_,

     # scope local: last backtrace
     '$@' => $@,
     '$!' => $!,

     # ractor local: stdin, out, err
     '$stdin'  => $stdin.inspect,
     '$stdout' => $stdout.inspect,
     '$stderr' => $stderr.inspect,
```

1 files changed, 1 insertions, 1 deletions

diff --git a/vm_core.h b/vm_core.h
index f644e8a6bc..8525bfcf3e 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -633,7 +633,7 @@ typedef struct rb_vm_struct {
     struct list_head workqueue; /* <=> rb_workqueue_job.jnode */
     rb_nativethread_lock_t workqueue_lock;
 
-    VALUE verbose, debug, orig_progname, progname;
+    VALUE orig_progname, progname;
     VALUE coverages;
     int coverage_mode;