/usr/lib/x86_64-linux-gnu/libOgreTerrain.so is in libogre-1.9-dev 1.9.0+dfsg1-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libOgreTerrain.so.1.9.0
/usr/lib/x86_64-linux-gnu/libOgreTerrain.so.1.9.0