fix segv on convifuration reloading

[sorc1]

On failed of success reloading, there are cases when we use log objects which point on freed shared memory.

To prevent that, we should:

• use the old log object when logging the new cycle events on failed reloading
• use the new log object when logging events related with the old cycle on success reloading

Also, we should alwayy update ngx_cleaner_event.log with the new log on success reloading.