Add a LPS benchmark variant which introduces artificial dependencies between successive lookups. While here, instead of writing the results from the lookups to a huge array, add them to an accumulator, in a more lightweight attempt at preventing the CPU's OOO machinery from discarding the lookup results if they would be completely unused.
net.route.test.run_lps_rnd measures LPS throughput with independent uniformly random keys
net.route.test.run_lps_rnd measures LPS throughput with uniformly random keys with artificial dependencies