/usr/include/OGRE/RenderSystems/ is in libogre-1.9-dev 1.9.0+dfsg1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/OGRE/RenderSystems/GL/
/usr/include/OGRE/RenderSystems/GL/GL/
/usr/include/OGRE/RenderSystems/GL/GL/gl.h
/usr/include/OGRE/RenderSystems/GL/GL/glew.h
/usr/include/OGRE/RenderSystems/GL/GL/glext.h
/usr/include/OGRE/RenderSystems/GL/GL/glxew.h
/usr/include/OGRE/RenderSystems/GL/GL/glxext.h
/usr/include/OGRE/RenderSystems/GL/GL/glxtokens.h
/usr/include/OGRE/RenderSystems/GL/GL/wglew.h
/usr/include/OGRE/RenderSystems/GL/GL/wglext.h
/usr/include/OGRE/RenderSystems/GL/GLX/
/usr/include/OGRE/RenderSystems/GL/GLX/OgreGLUtil.h
/usr/include/OGRE/RenderSystems/GL/GLX/OgreGLXContext.h
/usr/include/OGRE/RenderSystems/GL/GLX/OgreGLXGLSupport.h
/usr/include/OGRE/RenderSystems/GL/GLX/OgreGLXRenderTexture.h
/usr/include/OGRE/RenderSystems/GL/GLX/OgreGLXUtils.h
/usr/include/OGRE/RenderSystems/GL/GLX/OgreGLXWindow.h
/usr/include/OGRE/RenderSystems/GL/OgreGLATIFSInit.h
/usr/include/OGRE/RenderSystems/GL/OgreGLContext.h
/usr/include/OGRE/RenderSystems/GL/OgreGLDefaultHardwareBufferManager.h
/usr/include/OGRE/RenderSystems/GL/OgreGLDepthBuffer.h
/usr/include/OGRE/RenderSystems/GL/OgreGLFBOMultiRenderTarget.h
/usr/include/OGRE/RenderSystems/GL/OgreGLFBORenderTexture.h
/usr/include/OGRE/RenderSystems/GL/OgreGLFrameBufferObject.h
/usr/include/OGRE/RenderSystems/GL/OgreGLGpuNvparseProgram.h
/usr/include/OGRE/RenderSystems/GL/OgreGLGpuProgram.h
/usr/include/OGRE/RenderSystems/GL/OgreGLGpuProgramManager.h
/usr/include/OGRE/RenderSystems/GL/OgreGLHardwareBufferManager.h
/usr/include/OGRE/RenderSystems/GL/OgreGLHardwareIndexBuffer.h
/usr/include/OGRE/RenderSystems/GL/OgreGLHardwareOcclusionQuery.h
/usr/include/OGRE/RenderSystems/GL/OgreGLHardwarePixelBuffer.h
/usr/include/OGRE/RenderSystems/GL/OgreGLHardwareVertexBuffer.h
/usr/include/OGRE/RenderSystems/GL/OgreGLNullStateCacheManagerImp.h
/usr/include/OGRE/RenderSystems/GL/OgreGLNullUniformCacheImp.h
/usr/include/OGRE/RenderSystems/GL/OgreGLPBRenderTexture.h
/usr/include/OGRE/RenderSystems/GL/OgreGLPBuffer.h
/usr/include/OGRE/RenderSystems/GL/OgreGLPixelFormat.h
/usr/include/OGRE/RenderSystems/GL/OgreGLPlugin.h
/usr/include/OGRE/RenderSystems/GL/OgreGLPrerequisites.h
/usr/include/OGRE/RenderSystems/GL/OgreGLRenderSystem.h
/usr/include/OGRE/RenderSystems/GL/OgreGLRenderTexture.h
/usr/include/OGRE/RenderSystems/GL/OgreGLRenderToVertexBuffer.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSLExtSupport.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSLGpuProgram.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSLLinkProgram.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSLLinkProgramManager.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSLPreprocessor.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSLProgram.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSLProgramFactory.h
/usr/include/OGRE/RenderSystems/GL/OgreGLStateCacheManager.h
/usr/include/OGRE/RenderSystems/GL/OgreGLSupport.h
/usr/include/OGRE/RenderSystems/GL/OgreGLTexture.h
/usr/include/OGRE/RenderSystems/GL/OgreGLTextureManager.h
/usr/include/OGRE/RenderSystems/GL/OgreGLUniformCache.h
/usr/include/OGRE/RenderSystems/GL/OgreSDLGLSupport.h
/usr/include/OGRE/RenderSystems/GL/OgreSDLPrerequisites.h
/usr/include/OGRE/RenderSystems/GL/OgreSDLWindow.h
/usr/include/OGRE/RenderSystems/GL/_ps1.0_parser.h
/usr/include/OGRE/RenderSystems/GL/_rc1.0_parser.h
/usr/include/OGRE/RenderSystems/GL/_ts1.0_parser.h
/usr/include/OGRE/RenderSystems/GL/_vs1.0_parser.h
/usr/include/OGRE/RenderSystems/GL/macro.h
/usr/include/OGRE/RenderSystems/GL/nvparse.h
/usr/include/OGRE/RenderSystems/GL/nvparse_errors.h
/usr/include/OGRE/RenderSystems/GL/nvparse_externs.h
/usr/include/OGRE/RenderSystems/GL/ps1.0_program.h
/usr/include/OGRE/RenderSystems/GL/rc1.0_combiners.h
/usr/include/OGRE/RenderSystems/GL/rc1.0_final.h
/usr/include/OGRE/RenderSystems/GL/rc1.0_general.h
/usr/include/OGRE/RenderSystems/GL/rc1.0_register.h
/usr/include/OGRE/RenderSystems/GL/ts1.0_inst.h
/usr/include/OGRE/RenderSystems/GL/ts1.0_inst_list.h
/usr/include/OGRE/RenderSystems/GL/vs1.0_inst.h
/usr/include/OGRE/RenderSystems/GL/vs1.0_inst_list.h