WinSock: Ensure to retrieve correct error code on Ruby 3.0

[ashie]

On Ruby 3.0, calling WSAGetLastError from Ruby script cannot get a
correct error code because Ruby's internal code resets it. Use
Fiddle.win32_last_socket_error instead if it's availbale.
You need fiddle 1.0.8 or later to use it. In addition, when you use
RubyInstaller, you need to specify the path of fiddle by RUBYLIB or
ruby -I at this moment because it loads Ruby's bundled fiddle before
initializing gem. This is the why we don't add a dependency to fiddle,
just only installing fiddle doesn't take effect.

e.g.)

gem install fiddle --version 1.0.8
set RUBYLIB=C:/Ruby30-x64/lib/ruby/gems/3.0.0/gems/fiddle-1.0.8/lib
bundle exec rake spec

See also:

• Unexpected error code with WSAGetLastError even though the previous function calll was failed ruby/fiddle#72
• https://bugs.ruby-lang.org/issues/17813
• https://github.com/oneclick/rubyinstaller2/blob/8225034c22152d8195bc0aabc42a956c79d6c712/lib/ruby_installer/build/dll_directory.rb

[ashie]

@repeatedly Could you take look this?

[ashie]

CI for Windows fails on a test but it's not this PR's issue:

Failures:
  1) ServerEngine::BlockingFlag wait_for_set timeout
     Failure/Error: elapsed.should >= 0.1 * 0.95
       expected: >= 0.095
            got:    0.093236
     # ./spec/blocking_flag_spec.rb:29:in `block (2 levels) in <top (required)>'

[kenhys]

@repeatedly Hi, could you kindly review this PR?

[repeatedly]

Looks good to me.

@td-dev Does anyone merge this?

[ashie]

Now I've got the permission.
Thank you for your review!