/usr/lib/x86_64-linux-gnu/libzmq.so.3 is in libzmq3 4.0.5+dfsg-2+deb8u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libzmq.so.3.1.0
/usr/lib/x86_64-linux-gnu/libzmq.so.3.1.0