/usr/lib/x86_64-linux-gnu/libxml2.so is in libxml2-dev 2.9.4+dfsg1-2.2+deb9u2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libxml2.so.2.9.4
/usr/lib/x86_64-linux-gnu/libxml2.so.2.9.4