darcs patch: fixes #317 (filter -threaded when profiling is on)

[Duncan Coutts]

On Mon, 2009-01-19 at 12:13 +0200, gleb.alexeev at gmail.com wrote:
> Fri Jan 16 19:08:05 EET 2009  gleb.alexeev at gmail.com
>   * fixes #317 (filter -threaded when profiling is on)

Thanks. I decided to apply a slight variation on your patch. It's a bit
longer but hopefully slightly clearer.

I checked it with darcs, but it needs another patch to darcs to stop it
using -threaded for the darcs lib, but then that's completely
unnecessary. I sent in a patch for that.

Duncan