This is not a Yii error, but a PHP error and it’s caused by having E_STRICT set in error_reporting. Check the PHP manual for further information on what values are available for error_reporting.
You could attach a handler to CApplications onError event. But you’d have to do this very early to cover as many situations as possible with your handler. Probably right in index.php before you call run() on your application object.
If all you need is logging, catch the error and warning log levels. Not sure if they contain these messages. But worth a try.