[Libreoffice] License statement

[Julien Chaffraix]

Hi fellow hackers,

All current and past contributions made to the LibreOffice project are
done under the GPLv3 / MPL or later version of these licenses.
Until further notice, all future contributions to the LibreOffice
project are available under the GPLv3 / MPL or later version of these
licenses.

Thanks,
Julien Chaffraix