GitLab

OpenVR by default includes its own jsoncpp.  However, we have one
in third_party already, so we don't need OpenVR's copy.

BUG=780987,790814,896087

Change-Id: Iac57998856ac72b36b6b731b3860ca67ae7c3f45
Reviewed-on: https://chromium-review.googlesource.com/c/1294669Reviewed-by: Klaus Weidner <klausw@chromium.org>
Commit-Queue: Bill Orr <billorr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602033}