DOCX export: Write contextualSpacing only if it takes place.

Change-Id: Ibc5783aeea8bcdc05c14054fa10c43a0c98c2159
diff --git a/sw/source/filter/ww8/docxattributeoutput.cxx b/sw/source/filter/ww8/docxattributeoutput.cxx
index 5cd7b31b..45bb751 100644
--- a/sw/source/filter/ww8/docxattributeoutput.cxx
+++ b/sw/source/filter/ww8/docxattributeoutput.cxx
@@ -5512,8 +5512,6 @@ void DocxAttributeOutput::FormatULSpace( const SvxULSpaceItem& rULSpace )
                OString::number( rULSpace.GetLower() ) );
        if (rULSpace.GetContext())
            m_pSerializer->singleElementNS( XML_w, XML_contextualSpacing, FSEND );
        else
            m_pSerializer->singleElementNS( XML_w, XML_contextualSpacing, FSNS( XML_w, XML_val ), "false", FSEND );
    }
}