/usr/include/qhull/QhullSets.h is in libqhull-dev 2012.1-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/include/qhull/../libqhullcpp/QhullSets.h
/usr/include/qhull/../libqhullcpp/QhullSets.h