This commits address build issues reported in issue #3268.
In particular, makes cleaner the dependency on parallel-netcdf
when +ncmpi variant is requested and adds CFLAGS=-D H5_USE_16_API
to handle the fact that Ior uses old 1.6 style APIs when +hdf5 is
requested.
These changes make Ior build fine and create modules for HDF5 versions
1.8.x and 1.10.0.
Even though build is successfull the modules haven't been tested in a
run.
