/usr/include/boost/nowide/ is in libleatherman-dev 1.4.0+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/boost/nowide/args.hpp
/usr/include/boost/nowide/cenv.hpp
/usr/include/boost/nowide/config.hpp
/usr/include/boost/nowide/convert.hpp
/usr/include/boost/nowide/cstdio.hpp
/usr/include/boost/nowide/cstdlib.hpp
/usr/include/boost/nowide/filebuf.hpp
/usr/include/boost/nowide/fstream.hpp
/usr/include/boost/nowide/integration/
/usr/include/boost/nowide/integration/filesystem.hpp
/usr/include/boost/nowide/iostream.hpp
/usr/include/boost/nowide/stackstring.hpp
/usr/include/boost/nowide/system.hpp
/usr/include/boost/nowide/utf8_codecvt.hpp
/usr/include/boost/nowide/windows.hpp