BUG/MEDIUM: lua: clean output buffer

When the txn.done() fiunction is called, the ouput buffer is cleaned,
but the associated relative pointer on the HTTP requests elements
is not reseted.

This patch remove this cleanup, because the output buffer may contain
data to forward.
diff --git a/src/hlua.c b/src/hlua.c
index 8fc85a6..5ee2337 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -4819,10 +4819,6 @@
 		htxn->s->txn->req.msg_state = HTTP_MSG_CLOSED;
 		htxn->s->txn->rsp.msg_state = HTTP_MSG_DONE;
 
-		/* Trim any possible response */
-		oc->buf->i = 0;
-		htxn->s->txn->rsp.next = htxn->s->txn->rsp.sov = 0;
-
 		/* Note that if we want to support keep-alive, we need
 		 * to bypass the close/shutr_now calls below, but that
 		 * may only be done if the HTTP request was already