/usr/share/doc/cpp-8-s390x-linux-gnu is in cpp-8-s390x-linux-gnu 8-20180414-1ubuntu2cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gcc-8-s390x-linux-gnu-base
/usr/share/doc/gcc-8-s390x-linux-gnu-base