When it failed, it always failed like this:

libreofficekit/qa/unit/tiledrendering.cxx:311:TiledRenderingTest::runAllTests
equality assertion failed
- Expected: 3

- Actual  :

It's not clear yet what triggers the failure, sounds like some kind of timing.

Change-Id: Ib5f44523f9a29c892aeda9eb881f452b57adb8a8
Reviewed-on: https://gerrit.libreoffice.org/36445Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>