/usr/lib/x86_64-linux-gnu/libflann.so.1.8 is in libflann1.8 1.8.4-4.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libflann.so.1.8.4
/usr/lib/x86_64-linux-gnu/libflann.so.1.8.4