patch applied (ghc): Haskell Program Coverage

[Simon Marlow]

Andy Gill wrote:

> The result of bootstrapping GHC, then running all the tests is  online, 
> BTW:
> 
>     http://www.galois.com/~andy/ghc/hpc_index.html

I've taken a better look over these results, everything looks plausible to me, 
which is great!  Some thoughts:

   - looks like the low-hanging fruit is to add some tests for the -ddump
     options and --show-iface, to cover all the pretty-printing code.  Even
     though we can't reasonably compare outputs from one run to the next, we
     can at least test that the Outputable instances don't panic.

   - Lots of panics and pprPanics are marked as not covered, quite rightly.
     However, it would be nice to be able to annotate these functions in some
     way to exclude them from the coverage tool: we can't test panics, because
     if one occurs it must be a bug.

Cheers,
	Simon