Disable optimization

[Henning Thielemann]

  I have upgraded to Cabal 1.2 while still using GHC-6.4.1. In the Haskore 
project there is the module NewResolutions.lhs which let GHC run into 
extensive swapping (certainly due to excessive memory consumption) on 
compilation when compiled with optimization. One can say, it cannot be 
compiled this way. This is clearly a compiler bug, but upgrading the 
compiler is not an option here. Thus I used unoptimized compilation so 
far. Now, Cabal 1.2 seems to have optimization set by default. While it 
was easy to add optimization by using 'GHC-Options' field it is not 
obvious how to override Cabal defaults.
  I don't think it was a good idea to switch on optimization silently from 
one Cabal version to another one. It would have been better to let people 
configure Cabal globally and manually to use optimization.