/usr/include/ClanLib-1.0/ClanLib/GL/ is in libclanlib-dev 1.0~svn3827-4.1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ClanLib-1.0/ClanLib/GL/light_source.h
/usr/include/ClanLib-1.0/ClanLib/GL/opengl.h
/usr/include/ClanLib-1.0/ClanLib/GL/opengl_state.h
/usr/include/ClanLib-1.0/ClanLib/GL/opengl_state_data.h
/usr/include/ClanLib-1.0/ClanLib/GL/opengl_surface.h
/usr/include/ClanLib-1.0/ClanLib/GL/opengl_window.h
/usr/include/ClanLib-1.0/ClanLib/GL/opengl_window_description.h
/usr/include/ClanLib-1.0/ClanLib/GL/opengl_wrap.h
/usr/include/ClanLib-1.0/ClanLib/GL/program_attribute.h
/usr/include/ClanLib-1.0/ClanLib/GL/program_object.h
/usr/include/ClanLib-1.0/ClanLib/GL/program_uniform.h
/usr/include/ClanLib-1.0/ClanLib/GL/setupgl.h
/usr/include/ClanLib-1.0/ClanLib/GL/shader_object.h
/usr/include/ClanLib-1.0/ClanLib/GL/texture.h
/usr/include/ClanLib-1.0/ClanLib/GL/viewpoint.h