Per patch from Tetsuya Mishima, ensure the rank_file mapper accurately tracks number of nodes in the map

Refs #4594
basesmuma: modify the minimum size for the large fan-in fan-out allreduce
algorithm

Per suggestion from Manju make sure there isn't a gap in the size ranges
for the available algorithms.

cmr=v1.8.2:ticket=#4437:reviewer=ompi-rm1.8