/usr/lib/x86_64-linux-gnu/libgnarl-4.6.so is in gnat-4.6 4.6.3-1ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgnarl-4.6.so.1
/usr/lib/x86_64-linux-gnu/libgnarl-4.6.so.1