/usr/include/crystalspace-2.0/iutil/ is in libcrystalspace-dev 2.0+dfsg-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/crystalspace-2.0/iutil/allocator.h
/usr/include/crystalspace-2.0/iutil/array.h
/usr/include/crystalspace-2.0/iutil/binder.h
/usr/include/crystalspace-2.0/iutil/cache.h
/usr/include/crystalspace-2.0/iutil/cfgfile.h
/usr/include/crystalspace-2.0/iutil/cfgmgr.h
/usr/include/crystalspace-2.0/iutil/cfgnotifier.h
/usr/include/crystalspace-2.0/iutil/cmdline.h
/usr/include/crystalspace-2.0/iutil/comp.h
/usr/include/crystalspace-2.0/iutil/csinput.h
/usr/include/crystalspace-2.0/iutil/databuff.h
/usr/include/crystalspace-2.0/iutil/dbghelp.h
/usr/include/crystalspace-2.0/iutil/document.h
/usr/include/crystalspace-2.0/iutil/evdefs.h
/usr/include/crystalspace-2.0/iutil/event.h
/usr/include/crystalspace-2.0/iutil/eventh.h
/usr/include/crystalspace-2.0/iutil/eventhandlers.h
/usr/include/crystalspace-2.0/iutil/eventnames.h
/usr/include/crystalspace-2.0/iutil/eventq.h
/usr/include/crystalspace-2.0/iutil/hiercache.h
/usr/include/crystalspace-2.0/iutil/job.h
/usr/include/crystalspace-2.0/iutil/kitchensink.h
/usr/include/crystalspace-2.0/iutil/memdebug.h
/usr/include/crystalspace-2.0/iutil/object.h
/usr/include/crystalspace-2.0/iutil/objreg.h
/usr/include/crystalspace-2.0/iutil/plugin.h
/usr/include/crystalspace-2.0/iutil/pluginconfig.h
/usr/include/crystalspace-2.0/iutil/reftrack.h
/usr/include/crystalspace-2.0/iutil/selfdestruct.h
/usr/include/crystalspace-2.0/iutil/string.h
/usr/include/crystalspace-2.0/iutil/stringarray.h
/usr/include/crystalspace-2.0/iutil/strset.h
/usr/include/crystalspace-2.0/iutil/systemopenmanager.h
/usr/include/crystalspace-2.0/iutil/threadmanager.h
/usr/include/crystalspace-2.0/iutil/timer.h
/usr/include/crystalspace-2.0/iutil/verbositymanager.h
/usr/include/crystalspace-2.0/iutil/vfs.h
/usr/include/crystalspace-2.0/iutil/virtclk.h
/usr/include/crystalspace-2.0/iutil/visualdebug.h