darcs patch: more portabilization

[Simon Marlow]

Isaac Dupree wrote:

> In other words, about 16 pieces of junk removed and 81 needed imports 
> added... but GHC modules usually import lots of what they need, so why 
> not?  _ILIT already needs to be imported from FastTypes.

Go ahead.  The current implicit import of FastString is a pain.

> Also, I'm thinking of changing all the things like
> 
> import GHC.IOBase
> to
> import GHC_EXTS.IOBase
> 
> with this in HsVersions.h:
> 
> /* This makes it easier to test building without GHC extensions,
>  * used in import statements such as "import GHC_EXTS.IOBase", to
>  * provide distinguishment from the GHC API's module GHC */
> #ifdef __GLASGOW_HASKELL__
> #define GHC_EXTS GHC
> #else
> /* let it be an error */
> #endif

I don't really see what this buys us - the only GHC.* modules are in 
package base anyway.

Cheers,
	Simon