/usr/lib/x86_64-linux-gnu/libgctp.so is in libgctp-dev 2.0-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgctp.so.0d
/usr/lib/x86_64-linux-gnu/libgctp.so.0d