/usr/lib/x86_64-linux-gnu/libfdt.so is in libfdt-dev 1.4.0+dfsg-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libfdt.so.1
/usr/lib/x86_64-linux-gnu/libfdt.so.1