Call-time pass-by-reference deprecated warning

In the d6 version of this module there are pass-by-reference warnings in voting_rules.content-types.inc. The PHP warnings are of the form:

PHP Warning: Call-time pass-by-reference has been deprecated; If you would like to pass it by reference, modify the declaration of voting_rules_condition_check_vote_tag_form(). 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 /opt/www/tng-upgrade/sites/all/modules/contrib/voting_rules/voting_rules.content-types.inc on line 135

There are a number of these in the include file. Attached patch simply removes the pass-by-reference since the called functions are already declared as references.