R1:2ae7d612f25a

Fix a missing pht() in Ponder

Summary: See <https://discourse.phabricator-community.org/t/translation-in-ponder/2630>.

Test Plan: Viewed a Ponder question page with no answers yet.

Reviewers: amckinley

Reviewed By: amckinley

Differential Revision: https://secure.phabricator.com/D20404