Fix notice: Call-time pass-by-reference

PHP Warning: Call-time pass-by-reference has been deprecated - argument passed by value; If you would like to pass it by reference, modify the declaration of file_set_status(). If you would like to enable call-time pass-by-reference, you can set allow_call_time_pass_reference to true in your INI file. However, future versions may not support this any longer. In sites/all/modules/yui_editor/plugins/img_upload.inc on line 26.

Can be solved by changing file_set_status(&$file, FILE_STATUS_PERMANENT); to file_set_status($file, FILE_STATUS_PERMANENT);

Referencing is taken care of in function file_set_status()