Update nofib submodule

to contain these commits:
   commit 8bffe3cb01ce404ab493de2b4316f2c1c4a9bda9
   Author: Joachim Breitner <mail@joachim-breitner.de>
   Date:   Fri Oct 2 10:09:17 2015 +0200

       Expected output of mandel when run under valgrind

       probably due to rounding/floating point precision numbers. It looks
       broken, but so does the existing file spectral/mandel/mandel.stdout-mingw.

   commit f9a577973edf6976e4c0703bf2afac900d7b6fd8
   Author: Gabor Greif <ggreif@gmail.com>
   Date:   Fri Jul 31 00:43:38 2015 +0200

       Typos in comments

   commit 20ae9113ad31eca426883544f597a3cae9b60d94
   Author: Simon Peyton Jones <simonpj@microsoft.com>
   Date:   Fri Apr 24 15:10:02 2015 +0100

       Add exact-real-arithmetic benchmark from David Lester

1 files changed, 0 insertions, 0 deletions

diff --git a/nofib b/nofib
-Subproject 85d10a442ccc36b953cabe300ae7c2cd0dae9a9
+Subproject 6480538c4665ad8f3863b1587bf83689dec2542