Validate on master broken.

[Andreas Klebinger]

Hello Devs,

it seems Simons patch "Smarter HsType pretty-print for promoted 
datacons" broke ./validate.



> I discovered that there were two copies of the PromotionFlag
>     type (a boolean, with helpfully named data cons), one in
>     IfaceType and one in HsType.  So I combined into one,
>     PromotionFlag, and moved it to BasicTypes. 

In particular haddock seems to have depended on the changed constructors.
If anyone with access and knowledge of haddock could fix  this I would 
be grateful.


Cheers
Andreas