/usr/lib/grass70/include/grass/defs/ is in grass-dev 7.0.3-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/grass70/include/grass/defs/Paintlib.h
/usr/lib/grass70/include/grass/defs/arraystats.h
/usr/lib/grass70/include/grass/defs/bitmap.h
/usr/lib/grass70/include/grass/defs/btree.h
/usr/lib/grass70/include/grass/defs/cdhc.h
/usr/lib/grass70/include/grass/defs/cluster.h
/usr/lib/grass70/include/grass/defs/colors.h
/usr/lib/grass70/include/grass/defs/datetime.h
/usr/lib/grass70/include/grass/defs/dbmi.h
/usr/lib/grass70/include/grass/defs/devlib.h
/usr/lib/grass70/include/grass/defs/dig_atts.h
/usr/lib/grass70/include/grass/defs/display.h
/usr/lib/grass70/include/grass/defs/form.h
/usr/lib/grass70/include/grass/defs/gis.h
/usr/lib/grass70/include/grass/defs/glocale.h
/usr/lib/grass70/include/grass/defs/gmath.h
/usr/lib/grass70/include/grass/defs/gprojects.h
/usr/lib/grass70/include/grass/defs/imagery.h
/usr/lib/grass70/include/grass/defs/la.h
/usr/lib/grass70/include/grass/defs/linkm.h
/usr/lib/grass70/include/grass/defs/manage.h
/usr/lib/grass70/include/grass/defs/neta.h
/usr/lib/grass70/include/grass/defs/nviz.h
/usr/lib/grass70/include/grass/defs/ogsf.h
/usr/lib/grass70/include/grass/defs/ortholib.h
/usr/lib/grass70/include/grass/defs/raster.h
/usr/lib/grass70/include/grass/defs/raster3d.h
/usr/lib/grass70/include/grass/defs/rbtree.h
/usr/lib/grass70/include/grass/defs/rowio.h
/usr/lib/grass70/include/grass/defs/segment.h
/usr/lib/grass70/include/grass/defs/spawn.h
/usr/lib/grass70/include/grass/defs/sqlp.h
/usr/lib/grass70/include/grass/defs/stats.h
/usr/lib/grass70/include/grass/defs/symbol.h
/usr/lib/grass70/include/grass/defs/vector.h
/usr/lib/grass70/include/grass/defs/vedit.h