Update bench.lua and update results

* bench.lua: Update to use an inner loop more like pflua-match's inner
  loop.  We run for less time though because we collect more samples.

* bench.mk (ITERATIONS?): Lower to 20, because although we run for less
  time than pflua-match we still run at least 100ms per sample so there
  is less wild variance.

* deps/pflua: Update to master.

* results: Update.