After auditing the four calls using this function, it's clear that none
of these fd's are ever meant to leak to a fork()'d process.

Created by VIM if .swp is already in use.

Per the creat() man page, creat() is equivalent to calling open
with flags of O_CREAT|O_WRONLY|O_TRUNC. Add O_CLOEXEC as well.

Only cut over when the heartbeat file is not being updated any longer.

Bug 4142.

Will write out a timestamp into a 'heartbeat' file in StateSaveLocation
every (SlurmctldTimeout / 4) seconds to demonstrate that the primary
controller still has access to the directory, and thus the backup
should avoid taking control.

Bug 4142.

The change from strncpy to strlcpy was chopping off the last character
of the name.

xgroup_set_param() avoids the string parsing overhead and
should be used instead.

Save re-parsing the input string back into the components.

Since ReleaseAgent is no longer required, we can strip out
all the supporting logic for it.

Accidentally removed bracked in checked-in code

If /proc was inaccessible proc_name would leak.

Put an explicit length cap in sprintf to avoid warning. The
size is checked immediate before here so this is just making
the 10-char limit explicit.

Bug 4062.

If the network path to shared storage used for the StateSaveLocation
is separate from that used to communicate with the cluster, both the
primary and backup controllers can end up acting as master on loss
of the cluster network.

Alter the HA takeover code path to make sure that the job state
save file is not still being updated by the primary slurmctld.
If it is, refuse to takeover and retry again later.

Bug 3592.

Bug 3921.

Bug 4062.

Bug 4084

bug 3824

Do not run the Node Health Check on termination of the external
  step as this happens when the job allocation ends and the job
  NHC will be executed anyway.
Bug 4074