Although <tag></tag> and <tag/> are syntactically equivalent, we
got a report that some 3rd party tool could not process a docx file
produced by LibreOffice. In styles.xml there was
<w14:ligatures w14:val="standardContextual"></w14:ligatures>
instead of
<w14:ligatures w14:val="standardContextual"/>
This patch is meant to fix this, to mimic what Word does anyway.
Change-Id: Iea409981d2a2eac40c460bdae4d3dc7e8b0c33ae
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/176680
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Jenkins