changed methis_partitioner to be compatabile with int64 datatype
changed methis_partitioner to be compatabile with int64 datatype

anshumang/gunrock-swched-swmm,ydwu/gunrock,vvishal/gunrock,Damien-/gunrock,vvishal/gunrock,Damien-/gunrock,ydwu/gunrock,ydwu/gunrock,anshumang/gunrock-swched-swmm,anshumang/gunrock-swched-swmm,Damien-/gunrock,vvishal/gunrock,ydwu/gunrock,Damien-/gunrock,ydwu/gunrock,Damien-/gunrock,anshumang/gunrock-swched-swmm,vvishal/gunrock,anshumang/gunrock-swched-swmm,vvishal/gunrock