perf.haskell.org functional again

[Joachim Breitner]

Hi,

after a system upgrade to avoid weird linker errors, and after some fixes in the nofib submodule, http://perf.haskell.org/ghc is running again.

I am collecting instruction counts instead of runtime, because the latter was just too often varying too wildly. I hope this will yield less false alarms.

I am also running nofib with mode=fast. This way, building GHC, running the testsuite and nofib takes a bit over one hour. I hope this can keep up with y'all's commits (when it took 2h it couldn't).

Now nothing of the setup requires a quiet dedicated machine, so if there is a need, we could move these builds into the cloud or into some CI infrastructure - but no changes are immediately planned.

Enjoy, Joachim