The use-case is to have a .svm and .pdf alternative, need to pick .pdf
from those.

The test fails with any of the below commits reverted:
- the xmloff part of this commit
- fda68426 (ODT export: add embedded pdf
support, 2016-06-27)
- 878a860d (vcl: add initial PDF
import-as-graphic filter, 2016-06-23)

Change-Id: Id5b298d25a46af6ce7aa5f8c71a29c3914e1a7ce
Reviewed-on: https://gerrit.libreoffice.org/26706Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>