Crash test update

[Caolán McNamara]

On Sun, 2021-04-18 at 09:05 +0000, crashtest wrote:
> New crashtest update available at  
> https://dev-builds.libreoffice.org/crashtest/988e2827319fa2fe04bb818880c1f381bd08a314/

There's a huge number of new import and export failures, mostly in
presentations. FWIW using tdf116803-1.odp as example it bisects to:

commit b94a2dc95dce8c67ddb9f01f7bd91da2a5759d9c
Date:   Thu Apr 15 17:39:48 2021 +0200

    threaded loading also for png loader