BUG/MINOR: lua: ensure large proxy IDs can be represented

In function hlua_fcn_new_proxy() too small a buffer was passed to
snprintf(), resulting in large proxy or listener IDs to make
snprintf() fail. It is unlikely to meet this case but let's fix it
anyway.

This fix must be backported to all stable branches where it applies.

src/hlua_fcn.c

@@ -838,7 +838,7 @@ int hlua_fcn_new_proxy(lua_State *L, struct proxy *px)
 	struct server *srv;
 	struct listener *lst;
 	int lid;
-	char buffer[10];
+	char buffer[17];
 
 	lua_newtable(L);
 
@@ -878,7 +878,7 @@ int hlua_fcn_new_proxy(lua_State *L, struct proxy *px)
 		if (lst->name)
 			lua_pushstring(L, lst->name);
 		else {
-			snprintf(buffer, 10, "sock-%d", lid);
+			snprintf(buffer, sizeof(buffer), "sock-%d", lid);
 			lid++;
 			lua_pushstring(L, buffer);
 		}