The gist of the problem: PACKAGE_VERSION_STATE is used in Setup.lhs and
nowhere else. Is it deprecated? Do we still need it?

A more detailed description of the actual problem I am facing:

One of the problems with the new XCode/new OSX is that Apple not only
decided to remove GCC, but also replace the GCC command with clang. 
http://www.haskell.org/haskellwiki/Mac_OS_X#Mac_OS_X_10.9_.28Mavericks.29.2C_Mac_OS_X_10.8_.28Mountain_Lion.29_and_Xcode_5

People therefore had to resort to using wrappers and other hacks.

Anyway, building darcs-branch-2.8 fails with the following log:
http://pastebin.com/zVK2GkRz

I think there might be a problem with a wrapper script I am using:
http://www.haskell.org/pipermail/haskell-cafe/2013-October/111174.html

However, I've removed the line from Setup.lhs and managed to build and
use darcs just fine.