BUILD: fix compilation error with DEBUG_FULL

Recent changes in structures broke the compilation when using DEBUG_FULL.
Let's update apply the changes also to the variables used in DPRINTF calls.
diff --git a/src/proto_tcp.c b/src/proto_tcp.c
index 1e97e8e..7c3258c 100644
--- a/src/proto_tcp.c
+++ b/src/proto_tcp.c
@@ -782,7 +782,7 @@
 		req,
 		req->rex, req->wex,
 		req->flags,
-		req->i,
+		req->buf.i,
 		req->analysers);
 
 	/* We don't know whether we have enough data, so must proceed
@@ -901,7 +901,7 @@
 		rep,
 		rep->rex, rep->wex,
 		rep->flags,
-		rep->i,
+		rep->buf.i,
 		rep->analysers);
 
 	/* We don't know whether we have enough data, so must proceed