Use server_port for Windows

fix r41686 [Bug #8574]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41802 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* 2013-07-06

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41803 b2dd03c8-39d4-4d8f-98ff-823fe69b080e