Add support for node-specific "arch" (architecture) and "os" (operating

    system) fields. These fields are set based upon values reported by the
    slurmd daemon on each compute node using SLURM_ARCH and SLURM_OS environment
    variables (if set, the uname function otherwise) and are intended to support
    changes in real time changes in operating system. These values are reported
    by "scontrol show node" plus the sched/wiki and sched/wiki2 plugins for Maui
    and Moab respectively.