/usr/ is in libgsystem-dev 2015.2+deb-4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/x86_64-linux-gnu/libgsystem.so
/usr/include/
/usr/include/libgsystem/
/usr/include/libgsystem/gsystem-console.h
/usr/include/libgsystem/gsystem-errors.h
/usr/include/libgsystem/gsystem-file-utils.h
/usr/include/libgsystem/gsystem-glib-compat.h
/usr/include/libgsystem/gsystem-local-alloc.h
/usr/include/libgsystem/gsystem-log.h
/usr/include/libgsystem/gsystem-shutil.h
/usr/include/libgsystem/gsystem-subprocess-context.h
/usr/include/libgsystem/gsystem-subprocess.h
/usr/include/libgsystem/libgsystem.h
/usr/lib/
/usr/lib/x86_64-linux-gnu/
/usr/lib/x86_64-linux-gnu/pkgconfig/
/usr/lib/x86_64-linux-gnu/pkgconfig/libgsystem.pc
/usr/share/
/usr/share/doc/
/usr/share/doc/libgsystem-dev/
/usr/share/doc/libgsystem-dev/changelog.Debian.gz
/usr/share/doc/libgsystem-dev/copyright
/usr/share/gir-1.0/
/usr/share/gir-1.0/GSystem-1.0.gir