Without that, Request::waitProcessMessages might wait indefinitely for
Application::Yield() to return; while the latter would wait for a message
in GetMessage. If there's no visible LO window, the message might never
arrive by itself.
Co-authored-by: Jan-Marek Glogowski <glogow@fbihome.de>

Change-Id: Ie2622053a8d4467eb1cbd579d8496cb5ddef08aa
Reviewed-on: https://gerrit.libreoffice.org/70346Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Tested-by: Mike Kaganski <mike.kaganski@collabora.com>