Ensure that mpirun correctly selects the HNP ess component without attempting to init the PMI subsystem as mpirun won't be supported anyway, so let's avoid the error message. Also, daemons launched by the plm/slurm component must use the ess/slurm module as we cannot trust the Slurm PMI_Init functions to correctly tell us when PMI support is available.
Remove the no-longer-used variables from the opal_hash_table_t definition, and their reference in the ompi debugger code.