[MEDIUM] use buffer_check_timeouts instead of stream_sock_check_timeouts()

It's more appropriate to use buffer_check_timeouts() to check for buffer
timeouts and si->shutw/shutr to shutdown the stream interfaces.
diff --git a/include/proto/stream_sock.h b/include/proto/stream_sock.h
index 45064be..d005be5 100644
--- a/include/proto/stream_sock.h
+++ b/include/proto/stream_sock.h
@@ -36,6 +36,7 @@
 int stream_sock_data_check_timeouts(int fd);
 int stream_sock_data_update(int fd);
 int stream_sock_data_finish(int fd);
+int stream_sock_shutr(struct stream_interface *si);
 int stream_sock_shutw(struct stream_interface *si);