SIGUSR2 in slurmd would re-open the logging files on signal-driven
  basis, possibly resulting in deadlock due to interrupting a running
  thread.
bug 4281

Use %m instead, and print the raw number for posterity.

CID 178117

CID 178118, 178119

Coverity CID 144120

Coverity CID 48915

E.g., gpu:tesla:2 would have parsed as quantity "telsa" of gpu.
Change the index value to the end of the array (-1 index value).

Bug 4250.

GCC is complaining when incrementing a boolean variable, it should
be assigned a value of true or false, and not incremented with ++.

Bug 4212.

Bug 4171

Rather than end up with "%.-1s" printed out in the output as snprintf
refused to parse the format specifier.

Bug 4164.

Now that the x11_forwarding code is running under seteuid/setegid,
and not using _become_user in the stepd, the environment is not set
automatically so xauth was trying to alter /root/.Xauthority instead
of the user's. (That restriction is in place so hostkey auth can work
safely.)

While here, move the xauth cleanup into the x11 forwarding shutdown
thread and out of the stepd's mgr.c.

Caught by -Werror=unused-result.

x11 flags come in the cred here, not in the msg.

For reasons that aren't quite clear, this causes quite a few failures
in the regression suite.

As the X11 race has been solved elsewhere, reverting this is the safest
option for now.

This reverts commit 34b67180332cfec6f4a72cc79c670bd73395c3b7.

This fixes a weird issue where new X11 applications will not be
able to start rendering on screen until an input even is forced
on the other X11 connections, e.g. by moving your mouse over them.

This has something to do with complications of the non-blocking I/O
in libssh2, but I'm at a loss to better describe why this make it
work correctly.

Shut down in a slightly nicer fashion by closing the listening
port and ssh connection properly.

The prolog is marked complete as soon as job_manager starts.
However, this is well before the extern step setup has actually
had time to complete, which leads to a race condition in the x11
code where the display has not been established.

Adding this locking keeps _handle_x11_display from returning
until the display number has been set.

Make this consistent with x11_remove_xauth.

Used to cleanup the magic cookie added earlier by x11_set_xauth.

Determine if this node has x11 forwarding enabled based
on the node index, and only setup forwarding or alter the DISPLAY
variable if appropriate.

The batch step for a job in the only batch step,
so simplify this info message. And switch to %u for uid.

Throw an error if enabled but the build had it disabled.

Reject jobs with X11 flags set if the support is not enabled,
and add an appropriate error code for this case.

- Do not re-launch the extern step if !first_run.
- Move before _remove_job_running_prolog() to make sure the
  extern step has at least a slight head start before steps can
  launch. Note that this only ensures the stepd has started, but
  not that the stepd is finished it's own internal setup - further
  work in slurmstepd would be required to remove this race completely.

Bug 4264.