handle HUP on any mode socket

I am using libwebsockets on Windows 7 in external poll mode.
I am finding that if I present a socket fd on a normal HTTP connection
(LWS_CONNMODE_HTTP_SERVING:) to libwebsocket_service_fd with just a HUP
event, the event doesn't get handled but revents gets cleared indicating
that the event has been handled.  Should it be handled in the same way
as LWS_CONNMODE_WS_SERVING?

(Modified by AG to apply to all sockets)

Signed-off-by: Andy Green <andy.green@linaro.org>
Signed-off-by: Graham Newton <gnewton@peavey-eu.com>