Manually add preInclude cabal_macros.h in cpphs options

[phischu]

I tried to use hs-gen-iface with cabal i.e.:

cabal install --haskell-suite -w hs-gen-iface transformers

It failed with

hs-gen-iface: Cannot expand #if directive in file ./Control/Monad/Trans/Error.hs  at line 60 col 1:
    MIN_VERSION_base(a,b,c) is not a defined macro

cabal_macros.h is not in the preInclude field of the cpphs options given to hs-gen-iface by cabal but I believe it should be. This is not a fix but a workaround.

Using haskell/cabal@944d507

[UnkindPartition]

Thanks for the report. The proper place to take care of this is haskell-packages. I filed this under haskell-suite/haskell-packages#15