This way we actually continue when we're ready to, rather than
dumbly hoping we wait for long enough.

This isn't entirely unproblematic though -- if we have no config
pre-prepared (i.e. first-run), then we just end up hanging on this
since soffice_main exits without doing anything to the OfficeIPCThread.
(Which is especially problematic for unit tests which specifically run
 on an empty config.)

Change-Id: I064fb500a224cfe37a0d3ba24b6154ffd72a71a3