call qsprintf() without warnings

Summary:
After T13217 import_repository_symbols.php was showing a lot of warnings, using %LQ fixes that.
I'm aware, that there are changes planned to the whole managing the symbols complex but until then less warnings are nice.

Test Plan: No more warnings when updating symbols

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Differential Revision: https://secure.phabricator.com/D19962