/usr/lib/x86_64-linux-gnu/libgsystem.so is in libgsystem-dev 2015.2+deb-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgsystem.so.0.0.0
/usr/lib/x86_64-linux-gnu/libgsystem.so.0.0.0