Fix statically linked applications to CRAY's PMI.

Statically linked Cray PMI applications still expect to use some file paths
containing the old SLURM_ID_HASH format. Some Cray customers have
certification requirements that make recompilation difficult.

The attached patch defines a macro to convert the new SLURM_ID_HASH
to the old format, and writes the files and symlinks necessary for statically
linked Cray PMI applications to work.

Bug 4114