/usr/include/osmium/osm/ is in libosmium-dev 0.0~20111213-g7f3500a-3build5.
This file is owned by root:root, with mode 0o755.
..
/usr/include/osmium/osm/area.hpp
/usr/include/osmium/osm/bounds.hpp
/usr/include/osmium/osm/meta.hpp
/usr/include/osmium/osm/node.hpp
/usr/include/osmium/osm/object.hpp
/usr/include/osmium/osm/position.hpp
/usr/include/osmium/osm/relation.hpp
/usr/include/osmium/osm/relation_member.hpp
/usr/include/osmium/osm/relation_member_list.hpp
/usr/include/osmium/osm/tag.hpp
/usr/include/osmium/osm/tag_list.hpp
/usr/include/osmium/osm/types.hpp
/usr/include/osmium/osm/way.hpp
/usr/include/osmium/osm/way_node.hpp
/usr/include/osmium/osm/way_node_list.hpp