/usr/lib/x86_64-linux-gnu/libgecodeint.so is in libgecode-dev 4.2.1-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgecodeint.so.36.0
/usr/lib/x86_64-linux-gnu/libgecodeint.so.36.0