* When fabrics=auto or schedulers=auto, the intent is to defer to the
OpenMPI configure and let it determine and use what it finds
available on the system. The current behavior for 'with_or_without'
in the case of 'auto' explicitly disables all possible values.
This updates the logic to call 'with_or_without' only when the
value of fabrics/schedulers is not 'auto'.
* To allow explicitly disabling all fabrics/schedulers, each of these
variants has added support for 'none' (which is also the default
value).
* Add a conflict for the loadleveler scheduler for openmpi-3 and
above as it is no longer a valid configure option.
d1ea5ba2cd