fix some mixed space+tab indentation

This fixes all instances of " \t" in the code base. Most common case
seems to be after a "where" line; probably vim copied the two space layout
of that line.

Done as a background task while listening to episode 2 of the Type Theory
podcast.

Utility/CopyFile.hs

@@ -47,10 +47,10 @@ createLinkOrCopy :: FilePath -> FilePath -> IO Bool
 #ifndef mingw32_HOST_OS
 createLinkOrCopy src dest = go `catchIO` const fallback
   where
-  	go = do
+	go = do
 		createLink src dest
 		return True
-  	fallback = copyFileExternal CopyAllMetaData src dest
+	fallback = copyFileExternal CopyAllMetaData src dest
 #else
 createLinkOrCopy = copyFileExternal CopyAllMetaData
 #endif