/usr/lib/x86_64-linux-gnu/libstemmer.so is in libstemmer-dev 0+svn546-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libstemmer.so.0d.0.0
/usr/lib/x86_64-linux-gnu/libstemmer.so.0d.0.0