/usr/include/osgGA/ is in libopenscenegraph-3.4-dev 3.4.0+dfsg1-4+b3.
This file is owned by root:root, with mode 0o755.
..
/usr/include/osgGA/AnimationPathManipulator
/usr/include/osgGA/CameraManipulator
/usr/include/osgGA/CameraViewSwitchManipulator
/usr/include/osgGA/Device
/usr/include/osgGA/DriveManipulator
/usr/include/osgGA/Event
/usr/include/osgGA/EventHandler
/usr/include/osgGA/EventQueue
/usr/include/osgGA/EventVisitor
/usr/include/osgGA/Export
/usr/include/osgGA/FirstPersonManipulator
/usr/include/osgGA/FlightManipulator
/usr/include/osgGA/GUIActionAdapter
/usr/include/osgGA/GUIEventAdapter
/usr/include/osgGA/GUIEventHandler
/usr/include/osgGA/KeySwitchMatrixManipulator
/usr/include/osgGA/MultiTouchTrackballManipulator
/usr/include/osgGA/NodeTrackerManipulator
/usr/include/osgGA/OrbitManipulator
/usr/include/osgGA/SphericalManipulator
/usr/include/osgGA/StandardManipulator
/usr/include/osgGA/StateSetManipulator
/usr/include/osgGA/TerrainManipulator
/usr/include/osgGA/TrackballManipulator
/usr/include/osgGA/UFOManipulator
/usr/include/osgGA/Version
/usr/include/osgGA/Widget