All of the code for voting in Bugzilla has been moved into an extension, called "Voting", in the extensions/Voting/ directory. To enable it, you must remove the disabled file from that directory, and run checksetup.pl.
Voting allows users to be given a pot of votes which they can allocate to bugs, to indicate that they'd like them fixed. This allows developers to gauge user need for a particular enhancement or bugfix. By allowing bugs with a certain number of votes to automatically move from "UNCONFIRMED" to "CONFIRMED", users of the bug system can help high-priority bugs garner attention so they don't sit for a long time awaiting triage.
To modify Voting settings:
Navigate to the "Edit product" screen for the Product you wish to modify
Maximum Votes per person: Setting this field to "0" disables voting.
Maximum Votes a person can put on a single bug: It should probably be some number lower than the "Maximum votes per person". Don't set this field to "0" if "Maximum votes per person" is non-zero; that doesn't make any sense.
Number of votes a bug in this product needs to automatically get out of the UNCONFIRMED state: Setting this field to "0" disables the automatic move of bugs from UNCONFIRMED to CONFIRMED.
Once you have adjusted the values to your preference, click "Update".