Removed the vendored git-lfs and the GitLfs build flag

AFAICS all git-annex builds are using the git-lfs library not the vendored
copy.

Debian stable now includes a new enough haskell-git-lfs package as well.
Last time this was tried it did not.

Remote/GitLFS.hs

@@ -7,7 +7,6 @@
 
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE CPP #-}
 
 module Remote.GitLFS (remote, gen, configKnownUrl) where
 
@@ -44,12 +43,7 @@ import Logs.Remote
 import Logs.RemoteState
 import qualified Git.Config
 
-#ifdef WITH_GIT_LFS
 import qualified Network.GitLFS as LFS
-#else
-import qualified Utility.GitLFS as LFS
-#endif
-
 import Control.Concurrent.STM
 import Data.String
 import Network.HTTP.Types