/usr/include/crystalspace-2.0/csutil/threading/ is in libcrystalspace-dev 2.0+dfsg-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/crystalspace-2.0/csutil/threading/atomicops.h
/usr/include/crystalspace-2.0/csutil/threading/atomicops_gcc_arm.h
/usr/include/crystalspace-2.0/csutil/threading/atomicops_gcc_generic.h
/usr/include/crystalspace-2.0/csutil/threading/atomicops_gcc_ppc.h
/usr/include/crystalspace-2.0/csutil/threading/atomicops_gcc_x86.h
/usr/include/crystalspace-2.0/csutil/threading/atomicops_msvc.h
/usr/include/crystalspace-2.0/csutil/threading/atomicops_sparc.h
/usr/include/crystalspace-2.0/csutil/threading/barrier.h
/usr/include/crystalspace-2.0/csutil/threading/condition.h
/usr/include/crystalspace-2.0/csutil/threading/mutex.h
/usr/include/crystalspace-2.0/csutil/threading/pthread_condition.h
/usr/include/crystalspace-2.0/csutil/threading/pthread_mutex.h
/usr/include/crystalspace-2.0/csutil/threading/pthread_thread.h
/usr/include/crystalspace-2.0/csutil/threading/pthread_tls.h
/usr/include/crystalspace-2.0/csutil/threading/rwmutex.h
/usr/include/crystalspace-2.0/csutil/threading/thread.h
/usr/include/crystalspace-2.0/csutil/threading/tls.h
/usr/include/crystalspace-2.0/csutil/threading/win32_apifuncs.h
/usr/include/crystalspace-2.0/csutil/threading/win32_condition.h
/usr/include/crystalspace-2.0/csutil/threading/win32_mutex.h
/usr/include/crystalspace-2.0/csutil/threading/win32_thread.h
/usr/include/crystalspace-2.0/csutil/threading/win32_tls.h