/usr/include/liblas/external/ is in liblas-dev 1.8.0-7build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/liblas/external/property_tree/
/usr/include/liblas/external/property_tree/detail/
/usr/include/liblas/external/property_tree/detail/exception_implementation.hpp
/usr/include/liblas/external/property_tree/detail/file_parser_error.hpp
/usr/include/liblas/external/property_tree/detail/info_parser_error.hpp
/usr/include/liblas/external/property_tree/detail/info_parser_read.hpp
/usr/include/liblas/external/property_tree/detail/info_parser_utils.hpp
/usr/include/liblas/external/property_tree/detail/info_parser_write.hpp
/usr/include/liblas/external/property_tree/detail/info_parser_writer_settings.hpp
/usr/include/liblas/external/property_tree/detail/json_parser_error.hpp
/usr/include/liblas/external/property_tree/detail/json_parser_read.hpp
/usr/include/liblas/external/property_tree/detail/json_parser_write.hpp
/usr/include/liblas/external/property_tree/detail/ptree_implementation.hpp
/usr/include/liblas/external/property_tree/detail/ptree_utils.hpp
/usr/include/liblas/external/property_tree/detail/rapidxml.hpp
/usr/include/liblas/external/property_tree/detail/xml_parser_error.hpp
/usr/include/liblas/external/property_tree/detail/xml_parser_flags.hpp
/usr/include/liblas/external/property_tree/detail/xml_parser_read_rapidxml.hpp
/usr/include/liblas/external/property_tree/detail/xml_parser_utils.hpp
/usr/include/liblas/external/property_tree/detail/xml_parser_write.hpp
/usr/include/liblas/external/property_tree/detail/xml_parser_writer_settings.hpp
/usr/include/liblas/external/property_tree/exceptions.hpp
/usr/include/liblas/external/property_tree/id_translator.hpp
/usr/include/liblas/external/property_tree/info_parser.hpp
/usr/include/liblas/external/property_tree/ini_parser.hpp
/usr/include/liblas/external/property_tree/json_parser.hpp
/usr/include/liblas/external/property_tree/ptree.hpp
/usr/include/liblas/external/property_tree/ptree_fwd.hpp
/usr/include/liblas/external/property_tree/ptree_serialization.hpp
/usr/include/liblas/external/property_tree/stream_translator.hpp
/usr/include/liblas/external/property_tree/string_path.hpp
/usr/include/liblas/external/property_tree/xml_parser.hpp