Replaced throw to throwIO where type is IO

[Simon Marlow]

On 24/09/10 23:20, Bas van Dijk wrote:
> I just extended the patch with two more throw-to-throwIO replacements
> in GHC/IO.hs.
>

We should be using throwIO rather than throw in an IO context, so if 
there are no objections I'll test and apply the patch.  It's not an API 
or a functionality change, so I don't think the full libraries proposal 
process is warranted here.

I'm sure none of these are actually bugs, but it's good practice to use 
throwIO.  Unfortunately there's no easy way to get the type system to 
tell us.

Cheers,
	Simon