/usr/include/ is in libqwtplot3d-qt5-dev 0.2.7+svn191+gcc7-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/qwtplot3d/
/usr/include/qwtplot3d/qwt3d_autoptr.h
/usr/include/qwtplot3d/qwt3d_autoscaler.h
/usr/include/qwtplot3d/qwt3d_axis.h
/usr/include/qwtplot3d/qwt3d_color.h
/usr/include/qwtplot3d/qwt3d_colorlegend.h
/usr/include/qwtplot3d/qwt3d_coordsys.h
/usr/include/qwtplot3d/qwt3d_drawable.h
/usr/include/qwtplot3d/qwt3d_enrichment.h
/usr/include/qwtplot3d/qwt3d_enrichment_std.h
/usr/include/qwtplot3d/qwt3d_function.h
/usr/include/qwtplot3d/qwt3d_global.h
/usr/include/qwtplot3d/qwt3d_graphplot.h
/usr/include/qwtplot3d/qwt3d_gridmapping.h
/usr/include/qwtplot3d/qwt3d_helper.h
/usr/include/qwtplot3d/qwt3d_io.h
/usr/include/qwtplot3d/qwt3d_io_gl2ps.h
/usr/include/qwtplot3d/qwt3d_io_reader.h
/usr/include/qwtplot3d/qwt3d_label.h
/usr/include/qwtplot3d/qwt3d_mapping.h
/usr/include/qwtplot3d/qwt3d_multiplot.h
/usr/include/qwtplot3d/qwt3d_openglhelper.h
/usr/include/qwtplot3d/qwt3d_parametricsurface.h
/usr/include/qwtplot3d/qwt3d_plot.h
/usr/include/qwtplot3d/qwt3d_portability.h
/usr/include/qwtplot3d/qwt3d_scale.h
/usr/include/qwtplot3d/qwt3d_surfaceplot.h
/usr/include/qwtplot3d/qwt3d_types.h
/usr/include/qwtplot3d/qwt3d_volumeplot.h