libwebsockets

lws_plat_fd add wsi to fops and helpers

Having the lws_context alone doesn't let us track state or act different
by wsi, which is the most interesting usecase.  Eg not only simply track
file position / decompression state per wsi but also act differently
according to wsi authentication state / associated cookies.

Signed-off-by: Andy Green <andy.green@linaro.org>