/usr/include/gromacs/fileio/ is in libgromacs-dev 5.1.2-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/gromacs/fileio/confio.h
/usr/include/gromacs/fileio/enxio.h
/usr/include/gromacs/fileio/filenm.h
/usr/include/gromacs/fileio/gmxfio.h
/usr/include/gromacs/fileio/matio.h
/usr/include/gromacs/fileio/mdoutf.h
/usr/include/gromacs/fileio/mtxio.h
/usr/include/gromacs/fileio/pdbio.h
/usr/include/gromacs/fileio/tpxio.h
/usr/include/gromacs/fileio/trajectory_writing.h
/usr/include/gromacs/fileio/trnio.h
/usr/include/gromacs/fileio/trx.h
/usr/include/gromacs/fileio/trxio.h
/usr/include/gromacs/fileio/xdr_datatype.h
/usr/include/gromacs/fileio/xtcio.h
/usr/include/gromacs/fileio/xvgr.h