/usr/include/garcon-1/garcon/ is in libgarcon-1-0-dev 0.4.0-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/garcon-1/garcon/garcon-config.h
/usr/include/garcon-1/garcon/garcon-environment.h
/usr/include/garcon-1/garcon/garcon-marshal.h
/usr/include/garcon-1/garcon/garcon-menu-directory.h
/usr/include/garcon-1/garcon/garcon-menu-element.h
/usr/include/garcon-1/garcon/garcon-menu-item-cache.h
/usr/include/garcon-1/garcon/garcon-menu-item-pool.h
/usr/include/garcon-1/garcon/garcon-menu-item.h
/usr/include/garcon-1/garcon/garcon-menu-merger.h
/usr/include/garcon-1/garcon/garcon-menu-node.h
/usr/include/garcon-1/garcon/garcon-menu-parser.h
/usr/include/garcon-1/garcon/garcon-menu-separator.h
/usr/include/garcon-1/garcon/garcon-menu-tree-provider.h
/usr/include/garcon-1/garcon/garcon-menu.h
/usr/include/garcon-1/garcon/garcon.h