/usr/mipsel-linux-gnu/lib64/debug/libstdc++.so is in lib64stdc++6-6-dbg-mipsel-cross 6.4.0-17ubuntu1cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/mipsel-linux-gnu/lib64/debug/libstdc++.so.6.0.22