/usr/powerpc64le-linux-gnu/lib/libthread_db.so is in libc6-dev-ppc64el-cross 2.19-0ubuntu2cross0.2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/powerpc64le-linux-gnu/lib/libthread_db.so.1
/usr/powerpc64le-linux-gnu/lib/libthread_db.so.1