[racket] fannkuch-redux benchmark

Seems like the racket entries in the Computer Language Benchmarks Game
has no fannkuch-redux entry.  Isaac (the maintainer) said that we used
to have one, but the problem was changed (introduced a checksum).
There's also a nice description of a parallel solution on the problem
description page:

  http://shootout.alioth.debian.org/u32q/performance.php?test=fannkuchredux#about

so it looks like it could be a nice demonstration of using futures.

This is the old code we had:

  http://alioth.debian.org/scm/viewvc.php/shootout/bench/fannkuch/fannkuch.racket?view=markup&revision=1.1&root=shootout

which is also in collects/tests/racket/benchmarks/shootout.

If anyone wants to take it on, please mail me -- I'll add the code to
the repo (if you can't) and I'll send a revised version to the
shootout.

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                    http://barzilay.org/                   Maze is Life!