further split the locate kernel into locate & lookup to accelerate throughput
further split the locate kernel into locate & lookup to accelerate throughput

[git-p4: depot-paths = "//sw/gpgpu/nvbio/main/": change = 18271996]

kimrutherford/nvbio,kimrutherford/nvbio,NVlabs/nvbio,NVlabs/nvbio,NVlabs/nvbio,kimrutherford/nvbio,kimrutherford/nvbio,NVlabs/nvbio