BUG/MINOR: httpclient/lua: stuck when closing without data

The httpclient lua code is lacking the end callback, which means it
won't be able to wake up the lua code after a longjmp if the connection
was closed without any data.

Must be backported to 2.5.
diff --git a/src/hlua.c b/src/hlua.c
index 34d271f..b8dd0c7 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -7293,6 +7293,7 @@
 	hlua_hc->hc->ops.res_stline = hlua_httpclient_cb;
 	hlua_hc->hc->ops.res_headers = hlua_httpclient_cb;
 	hlua_hc->hc->ops.res_payload = hlua_httpclient_cb;
+	hlua_hc->hc->ops.res_end = hlua_httpclient_cb;
 
 	/* a body is available, it will use the request callback */
 	if (body_str) {