... and adapt makefiles to automatically rebuild everything that depends
on PYTHON_VERSION.

Change-Id: If468183e59463503051c2a1526a905dbee9bf4cb
Reviewed-on: https://gerrit.libreoffice.org/17818Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Stahl <mstahl@redhat.com>