The "xlink" prefix for the "xlink:href" attribute on the "image" element
was not bound.

Change-Id: I473a0b1612b4842cf84a264960bb28a9f19600e5
Reviewed-on: https://gerrit.libreoffice.org/49612Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>
Tested-by: Jenkins <ci@libreoffice.org>