Use more proper integer types

Change-Id: I33bbe7bf21a0758b9f59d78c8e2a32936f845eac
diff --git a/sw/source/filter/ww8/rtfexport.cxx b/sw/source/filter/ww8/rtfexport.cxx
index ac6f2f6..8fec63d 100644
--- a/sw/source/filter/ww8/rtfexport.cxx
+++ b/sw/source/filter/ww8/rtfexport.cxx
@@ -1113,7 +1113,7 @@ sal_uInt16 RtfExport::GetRedline(const OUString& rAuthor)
    if (i != m_aRedlineTable.end())
        return i->second;

    int nId = m_aRedlineTable.size();
    const sal_uInt16 nId = static_cast<sal_uInt16>(m_aRedlineTable.size());
    m_aRedlineTable.insert(std::pair<OUString,sal_uInt16>(rAuthor,nId));
    return nId;
}