/usr/lib/x86_64-linux-gnu/gambit4/libgambit.so is in libgambit4-dev 4.8.8-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/gambit4/libgambit.so.4
/usr/lib/x86_64-linux-gnu/gambit4/libgambit.so.4