/usr/lib/x86_64-linux-gnu/libgnutls-extra.so is in libgnutls-dev 2.12.14-5ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgnutls-extra.so.26.21.8
/usr/lib/x86_64-linux-gnu/libgnutls-extra.so.26.21.8