/usr/lib/x86_64-linux-gnu/libgecodeint.so is in libgecode-dev 5.1.0-2build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgecodeint.so.44.0
/usr/lib/x86_64-linux-gnu/libgecodeint.so.44.0