* lib/webrick/server.rb: Use a pipe to detect server shutdown.
  shutdown() or close() for listening socket is not a reliable.
  Actually, both doesn't work (doesn't wake up select()) on
  DragonFly BSD 3.6.2.

* test/webrick/utils.rb: :ShutdownSocketWithoutClose is not required
  now to immediate server shutdown detection.
  This fixes fd leaks.

* test/net/http/utils.rb: Ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46253 b2dd03c8-39d4-4d8f-98ff-823fe69b080e