make configs shareable when frozen

ext/openssl/ossl_config.c

@@ -22,7 +22,7 @@ static const rb_data_type_t ossl_config_type = {
     {
         0, nconf_free,
     },
-    0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED,
+    0, 0, RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED | RUBY_TYPED_FROZEN_SHAREABLE,
 };
 
 CONF *

test/openssl/test_config.rb

@@ -277,6 +277,15 @@ def test_dup
     assert_equal(@it.sections.sort, c2.sections.sort)
   end
 
+  if respond_to?(:ractor)
+    ractor
+    def test_ractor
+      assert(Ractor.shareable?(@it))
+      assert(Ractor.shareable?(OpenSSL::Config.parse("[empty]\n")))
+      assert(Ractor.shareable?(OpenSSL::Config::DEFAULT_CONFIG_FILE))
+    end
+  end
+
   private
 
   def in_tmpdir(*args)