Don't yet treat package registration files as UTF8

Though we'll probably need to do so eventually because they contain many of
the same fields as the .cabal files which are UTF8. This will need agreement
with ghc-pkg.

Distribution/Simple/Register.hs

@@ -68,7 +68,7 @@ import Distribution.InstalledPackageInfo
 	 emptyInstalledPackageInfo)
 import qualified Distribution.InstalledPackageInfo as IPI
 import Distribution.Simple.Utils
-         ( createDirectoryIfMissingVerbose, copyFileVerbose, writeUTF8File
+         ( createDirectoryIfMissingVerbose, copyFileVerbose
          , die, info, notice, setupMessage )
 import Distribution.System
 
@@ -172,7 +172,7 @@ writeInstalledConfig pkg_descr lbi inplace instConfOverride = do
   let instConfDefault | inplace   = inplacePkgConfigFile
                       | otherwise = installedPkgConfigFile
       instConf = fromMaybe instConfDefault instConfOverride
-  writeUTF8File instConf (pkg_config ++ "\n")
+  writeFile instConf (pkg_config ++ "\n")
 
 -- |Create a string suitable for writing out to the package config file
 showInstalledConfig :: PackageDescription -> LocalBuildInfo -> Bool