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.

Build/NullSoftInstaller.hs

@@ -103,7 +103,7 @@ makeInstaller gitannex license extrabins launchers = nsis $ do
 	name "git-annex"
 	outFile $ str installer
 	{- Installing into the same directory as git avoids needing to modify
- 	 - path myself, since the git installer already does it. -}
+	 - path myself, since the git installer already does it. -}
 	installDir gitInstallDir
 	requestExecutionLevel Admin