CPP macro to determine GHCi presence?

[Stephen Paul Weber]

Trying to cross-build the vector package I get:

> ghc-stage1: panic! (the 'impossible' happened)
>   (GHC version 7.7.20130123 for arm-unknown-nto-qnx):
> 	Cant do annotations without GHCi
>     {Data/Vector/Fusion/Stream/Monadic.hs:104:19-33}
>     base:GHC.Exts.ForceSpecConstr{d r2Qv}

This is because the source uses a feature that cannot be supported in 
cross-compilation.  The problematic line, however, can easily be removed.  
It would be very useful to have a CPP macro defined by GHC that can be used 
to enable/disable these sorts of features.

-- 
Stephen Paul Weber, @singpolyma
See <http://singpolyma.net> for how I prefer to be contacted
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