/usr/include/simgear/structure/ is in libsimgear-dev 3.4.0-3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/simgear/structure/OSGUtils.hxx
/usr/include/simgear/structure/OSGVersion.hxx
/usr/include/simgear/structure/SGAtomic.hxx
/usr/include/simgear/structure/SGBinding.hxx
/usr/include/simgear/structure/SGExpression.hxx
/usr/include/simgear/structure/SGPerfMon.hxx
/usr/include/simgear/structure/SGReferenced.hxx
/usr/include/simgear/structure/SGSharedPtr.hxx
/usr/include/simgear/structure/SGSmplhist.hxx
/usr/include/simgear/structure/SGSmplstat.hxx
/usr/include/simgear/structure/SGWeakPtr.hxx
/usr/include/simgear/structure/SGWeakReferenced.hxx
/usr/include/simgear/structure/Singleton.hxx
/usr/include/simgear/structure/StateMachine.hxx
/usr/include/simgear/structure/StringTable.hxx
/usr/include/simgear/structure/callback.hxx
/usr/include/simgear/structure/commands.hxx
/usr/include/simgear/structure/detail/
/usr/include/simgear/structure/detail/function_list_template.hxx
/usr/include/simgear/structure/event_mgr.hxx
/usr/include/simgear/structure/exception.hxx
/usr/include/simgear/structure/function_list.hxx
/usr/include/simgear/structure/intern.hxx
/usr/include/simgear/structure/map.hxx
/usr/include/simgear/structure/singleton.hpp
/usr/include/simgear/structure/subsystem_mgr.hxx