/usr/lib/x86_64-linux-gnu/libltdl.so is in libltdl-dev 2.4.2-1.7ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libltdl.so.7.3.0
/usr/lib/x86_64-linux-gnu/libltdl.so.7.3.0