debug step mode

3rd/lua/lstate.h

@@ -160,6 +160,7 @@ struct lua_State {
   struct lua_State *twups;  /* list of threads with open upvalues */
   struct lua_longjmp *errorJmp;  /* current error recover point */
   CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */
+  CallInfo temp_ci;  /* CallInfo for yield from hook (debug api use) */
   lua_Hook hook;
   ptrdiff_t errfunc;  /* current error handling function (stack index) */
   int stacksize;