/usr/lib/x86_64-linux-gnu/libgd.so is in libgd-dev 2.1.0-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgd.so.3.0.0
/usr/lib/x86_64-linux-gnu/libgd.so.3.0.0