Reverse handler for round robin channel selection in dragonfly model (Imported #154)

[nmcglo]

Original Issue Author: Misbah Mubarak
Original Issue ID: 154
Original Issue URL: https://xgitlab.cels.anl.gov/codes/codes/issues/154

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A round robin channel selection is being made for multiple chassis connections in sequential mode. However reverse handler for the round robin selection is non-intuitive since the function may be called several time when doing adaptive routing and we have to set a different flag every time the state has been modified in the function. Currently, the reverse handler functionality behaves like a randomized channel selection (since the saved state is not being restored in reverse function). We will have to find a better way to handle this in optimistic mode. Results of simulation vary slightly but are not significantly different.

Also see https://xgitlab.cels.anl.gov/codes/codes/issues/153