patch applied (cabal): Replace lots of configBlahDir fields with just one InstallDirs

[Duncan Coutts]

Sat Dec  8 10:26:20 PST 2007  Duncan Coutts <duncan at haskell.org>
  * Replace lots of configBlahDir fields with just one InstallDirs
  So instead of 10 fields like this:
  configPrefix   :: Maybe FilePath,
  ...
  we have just one compound one:
  configInstallDirs   :: InstallDirs (Maybe FilePath)
  Now that LocalBuildInfo and cabal-install's config use InstallDirs it makes
  converting a lot easier since we can use fmap and combineInstallDirs.
  This should also be easier to maintain as it has significantly reduced the
  number of places in the code you have to change when you add/change a dir.

    M ./Distribution/Simple/Configure.hs -15 +3
    M ./Distribution/Simple/InstallDirs.hs +1
    M ./Distribution/Simple/Setup.hs -45 +22