The fd was in different meanings on windows: POSIX read and write use the fd as a file descriptor. The gst_poll use the fd as a WSASocket. This patch use WSASocket as default on windows. This is a temporary measure, because IPC has many different implement. There may be a better way in the future. See #1044 Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1791>