R1:b44f687ce20d

Fix link to submodule's history

Test Plan:
https://secure.phabricator.com/diffusion/P/browse/master/externals/
Click on History of `javelin/`.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Koolvin

Differential Revision: https://secure.phabricator.com/D2316