For Docx files, the chart series names (labels)
    were rendered incorrectly and hence exported incorrectly.
    In place of the correct label, the series name
    for next series was displayed.

Change-Id: I988571d76d9c706ac2f7693881198bb604ec3fa8
Change-Id: I52631bc62fce46a43298c284cb11c2e8916fabe3
Reviewed-on: https://gerrit.libreoffice.org/6350Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>