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, 59 insertions, 0 deletions

diff --git a/bootstraptest/test_ractor.rb b/bootstraptest/test_ractor.rb
index eaa265fcfa..94570597ba 100644
--- a/bootstraptest/test_ractor.rb
+++ b/bootstraptest/test_ractor.rb
@@ -611,6 +611,65 @@ assert_equal 'ok', %q{
   'ok'
 }
 
+# $DEBUG, $VERBOSE are Ractor local
+assert_equal 'true', %q{
+  $DEBUG = true
+  $VERBOSE = true
+
+  def ractor_local_globals
+    /a(b)(c)d/ =~ 'abcd' # for $~
+    `echo foo`
+
+    {
+     # ractor-local (derived from created ractor): debug
+     '$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,
+    }
+  end
+  
+  h = Ractor.new do
+    ractor_local_globals
+  end.take
+  ractor_local_globals == h #=> true
+}
+
 # selfs are different objects
 assert_equal 'false', %q{
   r = Ractor.new do