Crash test update, formulagroup threading

[Caolán McNamara]

On Sun, 2017-12-10 at 18:16 +0100, Xisco Fauli wrote:
> I guess it's also related to
> https://bugs.documentfoundation.org/show_bug.cgi?id=114342

Yeah, looks like it to me. There's a preexisting recursion guard thing
in there, but its after the new threaded path, I imagine we need
something like https://gerrit.libreoffice.org/#/c/46195/ which works
for me there.