/usr/include/libqhullcpp/ is in libqhull-dev 2012.1-5.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libqhullcpp/Coordinates.h
/usr/include/libqhullcpp/PointCoordinates.h
/usr/include/libqhullcpp/Qhull.h
/usr/include/libqhullcpp/QhullError.h
/usr/include/libqhullcpp/QhullFacet.h
/usr/include/libqhullcpp/QhullFacetList.h
/usr/include/libqhullcpp/QhullFacetSet.h
/usr/include/libqhullcpp/QhullHyperplane.h
/usr/include/libqhullcpp/QhullIterator.h
/usr/include/libqhullcpp/QhullLinkedList.h
/usr/include/libqhullcpp/QhullPoint.h
/usr/include/libqhullcpp/QhullPointSet.h
/usr/include/libqhullcpp/QhullPoints.h
/usr/include/libqhullcpp/QhullQh.h
/usr/include/libqhullcpp/QhullRidge.h
/usr/include/libqhullcpp/QhullSet.h
/usr/include/libqhullcpp/QhullSets.h
/usr/include/libqhullcpp/QhullStat.h
/usr/include/libqhullcpp/QhullVertex.h
/usr/include/libqhullcpp/QhullVertexSet.h
/usr/include/libqhullcpp/RboxPoints.h
/usr/include/libqhullcpp/RoadError.h
/usr/include/libqhullcpp/RoadLogEvent.h
/usr/include/libqhullcpp/RoadTest.h
/usr/include/libqhullcpp/UsingLibQhull.h
/usr/include/libqhullcpp/functionObjects.h