/usr/lib/x86_64-linux-gnu/libbitcoin.so is in libbitcoin-dev 2.0-2.4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libbitcoin.so.0.0.0
/usr/lib/x86_64-linux-gnu/libbitcoin.so.0.0.0