Make Addrinfo objects Ractor shareable

Allow Addrinfo objects to be shared among Ractors.  Addrinfo objects are
already immutable, so I think it's safe for us to tag them as
RUBY_TYPED_FROZEN_SHAREABLE shareable too.

Author: tenderlove

ext/socket/raddrinfo.c

@@ -1211,6 +1211,7 @@ addrinfo_memsize(const void *ptr)
 static const rb_data_type_t addrinfo_type = {
     "socket/addrinfo",
     {addrinfo_mark, addrinfo_free, addrinfo_memsize,},
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_FROZEN_SHAREABLE,
 };
 
 static VALUE

test/socket/test_addrinfo.rb

@@ -360,6 +360,12 @@ def test_family_addrinfo
     assert_raise(Socket::ResolutionError) { Addrinfo.tcp("0.0.0.0", 4649).family_addrinfo("::1", 80) }
   end
 
+  def test_ractor_shareable
+    assert_ractor(<<~'RUBY', require: 'socket', timeout: 60)
+      Ractor.make_shareable Addrinfo.new "\x10\x02\x14\xE9\xE0\x00\x00\xFB\x00\x00\x00\x00\x00\x00\x00\x00".b
+    RUBY
+  end
+
   def random_port
     # IANA suggests dynamic port for 49152 to 65535
     # http://www.iana.org/assignments/port-numbers