realm: properly default -ll:ext_sysmem to 1
realm: properly default -ll:ext_sysmem to 1

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