* on Windows, pipe() creates sockets and not file descriptoes,

 * on Windows, pipe() creates sockets and not file descriptoes,
   hence we must use closesocket() to close a socket instead of
   close(). In addition, we should improve the closing of the
   socket (see http://tangentsoft.net/wskfaq/newbie.html#howclose)

 * use PIPE_FD_INVALID for invalid fd / socket

 * use PIPE_FD_ERROR for invalid result when sending / receiving
   data on fd / sockets

next step is to manage correctly errno on Windows with WSAGetLastError()
(see http://tangentsoft.net/wskfaq/articles/bsd-compatibility.html)

git-svn-id: http://svn.enlightenment.org/svn/e/trunk/ecore@40846 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33