configure.in: include winsock2.h
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48997 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: include winsock2.h
patch by Jon Forums in [ruby-core:67125]. [Bug #10640]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48997 b2dd03c8-39d4-4d8f-98ff-823fe69b080e