/usr/include/OGRE/Threading/ is in libogre-1.9-dev 1.9.0+dfsg1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/OGRE/Threading/OgreDefaultWorkQueue.h
/usr/include/OGRE/Threading/OgreDefaultWorkQueueStandard.h
/usr/include/OGRE/Threading/OgreDefaultWorkQueueTBB.h
/usr/include/OGRE/Threading/OgreThreadDefines.h
/usr/include/OGRE/Threading/OgreThreadDefinesBoost.h
/usr/include/OGRE/Threading/OgreThreadDefinesNone.h
/usr/include/OGRE/Threading/OgreThreadDefinesPoco.h
/usr/include/OGRE/Threading/OgreThreadDefinesTBB.h
/usr/include/OGRE/Threading/OgreThreadHeaders.h
/usr/include/OGRE/Threading/OgreThreadHeadersBoost.h
/usr/include/OGRE/Threading/OgreThreadHeadersPoco.h
/usr/include/OGRE/Threading/OgreThreadHeadersTBB.h