(stable) Fix a bad variable in global typehaead order/limit code

Summary: Ref T12538. I missed this in D17695, which renamed the variable. The logic was also a little off since jj is an index, not a count.

Test Plan: Typed con in global search, which hits "Con-pherence", "Con-duit" and "Con-fig", plus a bunch of other stuff. Got results after patch.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12538

Differential Revision: https://secure.phabricator.com/D17700