Remove deprecated call-time pass-by-reference

The following PHP warning is given by PHP every time the complete.module file is parsed:

PHP Warning: Call-time pass-by-reference has been deprecated; If you would like to pass it by reference, modify the declaration of [runtime function name](). 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 in .../complete/complete.module on line 257

It is fixed by the attached patch. See http://www.php.net/manual/en/language.references.pass.php for the general case.