Value stored to 'rc' is never read.

Add message type strings and job IDs where possible

Failed RPCs get requeued and retried with exponential backup.
Repeatedly failing RPCs get logged (need to improve that).

We were changing the buffers' processed offset to the beginning of the
body part of the offset to pack just the body part of the buffer but
once this happened we lost how much actual data was in the buffer. So we
were packing the whole buffer which could be larger than what was
actually being used in the buffer.

Changed job id print formats from %d to %u in several places

This reverts commit 831da38e.

Doesn't work with MySQL 5.7.17-0

Needed for federated cluster performance and locking issues

Log function name being logged, switch to use __func_ argument
  to prevent them from getting out of sync again

Report "MsgType=#" rather than just "Unknown"

Removing values in the middle of an enum will shift all of the values
and break backward compatability for old RPCs..
Broken in commit 1b0d9851

determine what the min, req and max node counts should be.

Cluster Features

Logic was removed in 9b1845a35ee3f.
Since if a federated job that can start now only sets the one sibling as
viable (used as an optimization to start jobs jobs without having to get
the lock from the origin), the viable siblings need to be gotten again.

to validate cluster features.

Add and remove siblings jobs based off new cluster features.

Now viable siblings -- siblings where siblings job could run on
(e.g. after requested cluster and cluster features applied) and active
siblings are distinguished. The remote sibling jobs only need to know
about the viable siblings and not the actual siblings. This simplies
things a little bit by not having to update the remote sibling jobs when
the active siblings change (e.g. cluster rejects the submission), only
when the viable siblings are changed (scontrol update clusterfeatures).

To catch locks going negative while in development.