MEDIUM: stream-interface: offer a generic chk_rcv function for connections

sock_raw and sock_ssl use a pretty generic chk_rcv function, so let's move
this function to the stream_interface and remove specific functions. Later
we might have a single chk_rcv function.
diff --git a/include/proto/stream_interface.h b/include/proto/stream_interface.h
index 5e2d74f..24072a6 100644
--- a/include/proto/stream_interface.h
+++ b/include/proto/stream_interface.h
@@ -39,6 +39,7 @@
 void stream_int_update_conn(struct stream_interface *si);
 int stream_int_shutr(struct stream_interface *si);
 int stream_int_shutw(struct stream_interface *si);
+void stream_int_chk_rcv_conn(struct stream_interface *si);
 
 extern struct sock_ops stream_int_embedded;
 extern struct sock_ops stream_int_task;