Periodically flush git command queue, to avoid boating memory usage too much.

Since the queue is flushed in between subcommand actions being run,
there should be no issues with actions that expect to queue up some stuff
and have it run after they do other stuff. So I didn't have to audit for
such assumptions.

Command/PreCommit.hs

@@ -11,6 +11,7 @@ import Control.Monad.State (liftIO)
 
 import Command
 import qualified Annex
+import qualified AnnexQueue
 import qualified GitRepo as Git
 import qualified Command.Add
 import qualified Command.Fix
@@ -42,5 +43,5 @@ cleanup file = do
 	-- stage the symlink
 	g <- Annex.gitRepo
 	liftIO $ Git.run g "reset" [Params "-q --", File file]
-	Annex.queueRun
+	AnnexQueue.flush True
 	return True