[MEDIUM] stream_interface: add and use ->update function to resync

We used to call stream_sock_data_finish() directly at the end of
a session update, but if we want to support non-socket interfaces,
we need to have this function configurable. Now we access it via
->update().
diff --git a/include/types/stream_interface.h b/include/types/stream_interface.h
index 7789323..c9b0e55 100644
--- a/include/types/stream_interface.h
+++ b/include/types/stream_interface.h
@@ -82,12 +82,13 @@
 	int fd;                 /* file descriptor for a stream driver when known */
 	unsigned int flags;
 	unsigned int exp;       /* wake up time for connect, queue, turn-around, ... */
-	int (*connect)(struct stream_interface *, struct proxy *, struct server *,
-		       struct sockaddr *, struct sockaddr *); /* connect function if any */
+	void (*update)(struct stream_interface *); /* update function */
 	void (*shutr)(struct stream_interface *);  /* shutr function */
 	void (*shutw)(struct stream_interface *);  /* shutw function */
 	void (*chk_rcv)(struct stream_interface *);/* chk_rcv function */
 	void (*chk_snd)(struct stream_interface *);/* chk_snd function */
+	int (*connect)(struct stream_interface *, struct proxy *, struct server *,
+		       struct sockaddr *, struct sockaddr *); /* connect function if any */
 	struct buffer *ib, *ob; /* input and output buffers */
 	unsigned int err_type;  /* first error detected, one of SI_ET_* */
 	void *err_loc;          /* commonly the server, NULL when SI_ET_NONE */