regent: Update Stencil mapper to use I/O proc by default.
regent: Update Stencil mapper to use I/O proc by default.

StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion,StanfordLegion/legion