/usr/lib/x86_64-linux-gnu/libgnutlsxx.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/libgnutlsxx.so.27.0.0
/usr/lib/x86_64-linux-gnu/libgnutlsxx.so.27.0.0