Incorrect free of rgi->deferred_events in parallel replication

Problem reported by nanyi607rao on maria-developers@:

...
else
{
if(!(rgi= new rpl_group_info(rli)))

{ my_error(ER_OUTOFMEMORY, MYF(0), (int)sizeof(*rgi)); return NULL; }

rgi->is_parallel_exec = true;

• if ((rgi->deferred_events_collecting= rli->mi->rpl_filter->is_on()))
  _ rgi->deferred_events= new Deferred_log_events(rli);
  }
  + if ((rgi->deferred_events_collecting= rli->mi->rpl_filter->is_on()))
  + rgi->deferred_events= new Deferred_log_events(rli);

because rgi->deferred_events was freed in rpl_parallel_thread::free_rgi() if it wasn't NULL