Change the ncounts argument to MPI_Count and use
MPI_Status_set_elements_x for enabling read/write operations beyond
the 2GB limit.
Thanks to Richard Warren from the HDF5 group for reporting the issue
and providing the suggested fix for romio.
Signed-off-by: Edgar Gabriel <egabriel@central.uh.edu>
(cherry picked from commit 8a3abbf80373bb36eb78688954118f1fb0cc2e9d)
6185fa1946