/usr/include/xalanc/XMLSupport/ is in libxalan-c-dev 1.11-6.
This file is owned by root:root, with mode 0o755.
..
/usr/include/xalanc/XMLSupport/FormatterToHTML.hpp
/usr/include/xalanc/XMLSupport/FormatterToNull.hpp
/usr/include/xalanc/XMLSupport/FormatterToText.hpp
/usr/include/xalanc/XMLSupport/FormatterToXML.hpp
/usr/include/xalanc/XMLSupport/FormatterToXMLUnicode.hpp
/usr/include/xalanc/XMLSupport/FormatterTreeWalker.hpp
/usr/include/xalanc/XMLSupport/XMLParserLiaison.hpp
/usr/include/xalanc/XMLSupport/XMLSupportDefinitions.hpp
/usr/include/xalanc/XMLSupport/XMLSupportException.hpp
/usr/include/xalanc/XMLSupport/XMLSupportInit.hpp
/usr/include/xalanc/XMLSupport/XalanDummyIndentWriter.hpp
/usr/include/xalanc/XMLSupport/XalanFormatterWriter.hpp
/usr/include/xalanc/XMLSupport/XalanHTMLElementsProperties.hpp
/usr/include/xalanc/XMLSupport/XalanIndentWriter.hpp
/usr/include/xalanc/XMLSupport/XalanOtherEncodingWriter.hpp
/usr/include/xalanc/XMLSupport/XalanUTF16Writer.hpp
/usr/include/xalanc/XMLSupport/XalanUTF8Writer.hpp
/usr/include/xalanc/XMLSupport/XalanXMLSerializerBase.hpp
/usr/include/xalanc/XMLSupport/XalanXMLSerializerFactory.hpp