MSWord uses \xb for linebreaks in DB fields, take 2 (bnc#878854)

This commit also does the conversion when reading the data from a data source
using the mail merge wizard.

Change-Id: Ia14417507b6ddce955fec26142a42ce51f77de4e
(cherry picked from commit 076e4afc61b216e34959bd4e3701f1fa19972d5c)
Reviewed-on: https://gerrit.libreoffice.org/9902
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>