[cabal] Extract simple static information from PackageDescription

[Henning Thielemann]

On Fri, 6 Nov 2015, Jakob Schöttl wrote:

> Thank you, Henning. I see, I need to handle this conditionals even if I don't 
> have such conditionals and flags in my cabal file.
>
> How can I resolve the conditionals?

I think, this one should help:
   https://www.haskell.org/cabal/release/cabal-latest/doc/API/Cabal/Distribution-PackageDescription-Configuration.html#v:flattenPackageDescription