Ruby

• ext/socket/extconf.rb: Set close_fds false for Cygwin.
  Cygwin doesn't support fd passing.
  This enables socket extension library cross-compilable by default.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40596 b2dd03c8-39d4-4d8f-98ff-823fe69b080e