/usr/lib/x86_64-linux-gnu/hdf5/serial/libhdf5.settings is in libhdf5-dev 1.10.0-patch1+docs-3+deb9u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/hdf5/serial/../../libhdf5_serial.settings