Packed ints performance test

Toke Eskildsen, te@ekot.dk, 20120629. See LUCENE-4062 for test code.

Measurements from 2 tests running at the same time. The i7 is quad-core and has enough RAM, so the limited resource in this scenario is memory cache.

te-prime: Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz, 8192 KB cache, JRE 1.6