/usr/lib/x86_64-linux-gnu/libdb_stl.so is in libdb5.1-stl-dev 5.1.29-7ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libdb_stl-5.1.so
/usr/lib/x86_64-linux-gnu/libdb_stl-5.1.so