/usr/include/osgEarthSymbology/ is in libosgearth-dev 2.9.0+dfsg-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/osgEarthSymbology/AGG.h
/usr/include/osgEarthSymbology/AltitudeSymbol
/usr/include/osgEarthSymbology/BBoxSymbol
/usr/include/osgEarthSymbology/BillboardResource
/usr/include/osgEarthSymbology/BillboardSymbol
/usr/include/osgEarthSymbology/Color
/usr/include/osgEarthSymbology/Common
/usr/include/osgEarthSymbology/CoverageSymbol
/usr/include/osgEarthSymbology/CssUtils
/usr/include/osgEarthSymbology/Expression
/usr/include/osgEarthSymbology/ExtrusionSymbol
/usr/include/osgEarthSymbology/Fill
/usr/include/osgEarthSymbology/GEOS
/usr/include/osgEarthSymbology/Geometry
/usr/include/osgEarthSymbology/GeometryFactory
/usr/include/osgEarthSymbology/GeometryRasterizer
/usr/include/osgEarthSymbology/IconResource
/usr/include/osgEarthSymbology/IconSymbol
/usr/include/osgEarthSymbology/InstanceResource
/usr/include/osgEarthSymbology/InstanceSymbol
/usr/include/osgEarthSymbology/LineSymbol
/usr/include/osgEarthSymbology/MarkerResource
/usr/include/osgEarthSymbology/MarkerSymbol
/usr/include/osgEarthSymbology/MeshConsolidator
/usr/include/osgEarthSymbology/MeshFlattener
/usr/include/osgEarthSymbology/MeshSubdivider
/usr/include/osgEarthSymbology/ModelResource
/usr/include/osgEarthSymbology/ModelSymbol
/usr/include/osgEarthSymbology/PointSymbol
/usr/include/osgEarthSymbology/PolygonSymbol
/usr/include/osgEarthSymbology/Query
/usr/include/osgEarthSymbology/RenderSymbol
/usr/include/osgEarthSymbology/Resource
/usr/include/osgEarthSymbology/ResourceCache
/usr/include/osgEarthSymbology/ResourceLibrary
/usr/include/osgEarthSymbology/Skins
/usr/include/osgEarthSymbology/StencilVolumeNode
/usr/include/osgEarthSymbology/Stroke
/usr/include/osgEarthSymbology/Style
/usr/include/osgEarthSymbology/StyleSelector
/usr/include/osgEarthSymbology/StyleSheet
/usr/include/osgEarthSymbology/Symbol
/usr/include/osgEarthSymbology/Tags
/usr/include/osgEarthSymbology/TextSymbol