make: error-out if USE_GASNET=1 and GASNET is undefined
make: error-out if USE_GASNET=1 and GASNET is undefined

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