[MEDIUM] acl: distinguish between request and response headers

hdr(x) will now still be used for request headers, and shdr(x) for
server headers (response).
diff --git a/src/client.c b/src/client.c
index 3995b53..87495a4 100644
--- a/src/client.c
+++ b/src/client.c
@@ -226,6 +226,7 @@
 			txn->status = -1;
 
 			txn->req.msg_state = HTTP_MSG_RQBEFORE; /* at the very beginning of the request */
+			txn->rsp.msg_state = HTTP_MSG_RPBEFORE; /* at the very beginning of the response */
 			txn->req.sol = txn->req.eol = NULL;
 			txn->req.som = txn->req.eoh = 0; /* relative to the buffer */
 			txn->auth_hdr.len = -1;