REORG: connection: move the target pointer from si to connection

The target is per connection and is directly used by the connection, so
we need it there. It's not needed anymore in the SI however.
diff --git a/src/backend.c b/src/backend.c
index ea0d894..845c93b 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -981,7 +981,7 @@
 	}
 
 	/* the target was only on the session, assign it to the SI now */
-	copy_target(&s->req->cons->target, &s->target);
+	copy_target(&s->req->cons->conn.target, &s->target);
 
 	/* set the correct protocol on the output stream interface */
 	if (s->target.type == TARG_TYPE_SERVER) {