/usr/lib/gcc-cross/s390x-linux-gnu/7/libgomp.so is in libgcc-7-dev-s390x-cross 7.3.0-16ubuntu3cross1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/gcc-cross/s390x-linux-gnu/7/../../../../s390x-linux-gnu/lib/libgomp.so.1