legion: fix compiler warning for trace allocations on systems with weird values for off_t
legion: fix compiler warning for trace allocations on systems with weird values for off_t

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