Commit() of related _Impl class actually wasn't called anywhere
after 465359c3 removed it from
destructor.

The config was also never tagged as modified, so fix that too.

Change-Id: I8293fee20ec154d5d70a7cda8b015bf723b50c87
Reviewed-on: https://gerrit.libreoffice.org/19558Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>
(cherry picked from commit 2e528df7)
Reviewed-on: https://gerrit.libreoffice.org/19688Reviewed-by: Norbert Thiebaud <nthiebaud@gmail.com>
(cherry picked from commit 7f5062f7)