This bug was sometimes setting a node's state to DRAINING instead of
DRAINED when there were no jobs on that node.

Perform some general code clean-up in those areas.

Convert xmalloc()/strcpy() to xstrdup().

shutdown only).

end_time to zero (previously was just setting the end_time so it looked
like the job ran for a huge time interval).

while fail/if too many then fatal/sleep and retry

 o Block SIGALRM by default
 o Only allow one thread to enter fwd_signal() at a time.

   blocked signals in threads.

   to "bar = xstrdup(foo);"

   to "bar = xstrdup(foo);":

  - use pthread_sigmask() instead of sigprocmask()
  - save blocked signals just before unblocking them in
    src/srun/allocate.c:allocate_nodes, then reinstate this mask before
    removing handlers.

Define new node configuration parameter for DOWN/DRAIN nodes: Reason=whatever.
Define node reason field for update and get info RPCs.
Slurmctld maintains the node reason, clears when node returned to service,
preserves value across restarts.

Define new node configuration parameter for DOWN/DRAIN nodes: Reason=whatever.
Define node reason field for update and get info RPCs.

Define new node configuration parameter for DOWN/DRAIN nodes: Reason=whatever.

multiple word node Reason values.

specifically to slurm controller.

   killed when a slurm_send times out. (resulting in confusing and misleading
   munge error message)