robustness protect and document ensure_user_space

Signed-off-by: Andy Green <andy.green@linaro.org>
problems in lws_handle_POLLOUT_event should just close

Signed-off-by: Andy Green <andy.green@linaro.org>
api change deliver socket fd to in param of extpoll callbacks

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