Setup.hs: unbreak 'runhaskell Setup configure' building mode
Setup.hs: unbreak 'runhaskell Setup configure' building mode

Otherwise default hook won't generate src/GitRev.hs file.

Signed-off-by: Sergei Trofimovich <110fdadc76b6bce16977f568bdb4723eaed6fb3f@gentoo.org>

TomMD/cryptol,GaloisInc/cryptol,GaloisInc/cryptol,TomMD/cryptol,ntc2/cryptol,TomMD/cryptol,TomMD/cryptol,GaloisInc/cryptol