* lib/webrick/utils.rb: use Socket.tcp_server_sockets to create server
  sockets.
  fix [Bug #7100] https://bugs.ruby-lang.org/issues/7100
  reported by sho-h (Sho Hashimoto).


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39551 b2dd03c8-39d4-4d8f-98ff-823fe69b080e