Use %s, not %d, to encode a 64-bit integer for a query

Summary: Fixes T5982. Probably. I'm just guessing here but like 95% sure this will fix it and 99% sure it won't hurt/break anything.

Test Plan: Still works on my 64-bit install, for what little that's worth.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T5982

Differential Revision: https://secure.phabricator.com/D10415