/usr/lib/x86_64-linux-gnu/libpolkit-agent-1.so is in libpolkit-agent-1-dev 0.105-15~deb8u2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libpolkit-agent-1.so.0.0.0
/usr/lib/x86_64-linux-gnu/libpolkit-agent-1.so.0.0.0