MINOR: channel: Forwad close to other side on abort

Most of calls to channel_abort() are associated to a call to
channel_auto_close(). Others are in areas where the auto close is the
default. So, it is now systematically enabled when an abort is performed on
a channel, as part of channel_abort() function.

include/haproxy/channel.h

@@ -565,6 +565,7 @@ static inline void channel_abort(struct channel *chn)
 {
 	chn_prod(chn)->flags |= SC_FL_SHUTR_NOW;
 	chn_cons(chn)->flags |= SC_FL_SHUTW_NOW;
+	chn->flags |= CF_AUTO_CLOSE;
 	chn->flags &= ~CF_AUTO_CONNECT;
 }