/usr/lib/x86_64-linux-gnu/hdf5/mpich/include is in libhdf5-mpich-dev 1.8.16+docs-4ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/hdf5/mpich/../../../../include/hdf5/mpich