REORG/MEDIUM: stream_interface: move applet->state and private to connection

The state and the private pointer are not specific to the applets, since SSL
will require exactly both of them. Move them to the connection layer now and
rename them. We also now ensure that both are NULL on first call.
diff --git a/include/proto/stream_interface.h b/include/proto/stream_interface.h
index 83c389a..632300a 100644
--- a/include/proto/stream_interface.h
+++ b/include/proto/stream_interface.h
@@ -114,6 +114,8 @@
 static inline void stream_interface_prepare(struct stream_interface *si, const struct sock_ops *ops)
 {
 	si->conn.data = ops;
+	si->conn.data_st = 0;
+	si->conn.data_ctx = NULL;
 }
 
 
diff --git a/include/types/stream_interface.h b/include/types/stream_interface.h
index ccaa1eb..2afefb5 100644
--- a/include/types/stream_interface.h
+++ b/include/types/stream_interface.h
@@ -110,6 +110,8 @@
 			int fd;       /* file descriptor for a stream driver when known */
 		} sock;
 	} t;
+	int data_st;                  /* data layer state, initialized to zero */
+	void *data_ctx;               /* general purpose pointer, initialized to NULL */
 };
 
 struct target {
@@ -164,8 +166,6 @@
 	int conn_retries;	/* number of connect retries left */
 	int send_proxy_ofs;	/* <0 = offset to (re)send from the end, >0 = send all */
 	struct {
-		int state;                 /* applet state, initialized to zero */
-		void *private;             /* may be used by any function above */
 		unsigned int st0, st1;     /* may be used by any function above */
 		union {
 			struct {