regent: Fix a bug in the check for nested non-predicated if/while.
regent: Fix a bug in the check for nested non-predicated if/while.

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