isc_uv_import must pass UV__IPC_SOCKET_XFER_TCP_CONNECTION, not SERVER.

As a leftover from old TCP accept code isc_uv_import passed TCP_SERVER flag when importing a socket on Windows. Since now we're importing/exporting accepted connections it needs to pass TCP_CONNECTION flag.

(cherry picked from commit 801f7af6)

Closes #1899 (closed)