get rid of racy addLink

The remaining callers all did not rely on it checking gitignore, so were
easy to convert.

They were susceptable to the same overwrite race as add and fix,
although less likely to have it and a narrower window than add's race.

Command.Rekey in passing got an unncessary call to removeFile deleted.
addSymlink handles deleting any existing worktree file.

Command/AddUnused.hs

@@ -30,9 +30,7 @@ start = startUnused "addunused" perform
 perform :: Key -> CommandPerform
 perform key = next $ do
 	logStatus key InfoPresent
-	-- Ignore the usual git ignores because the user has explictly
-	-- asked to add these files.
-	addLink (CheckGitIgnore False) file key Nothing
+	addSymlink file key Nothing
 	return True
   where
 	file = "unused." <> keyFile key

Command/AddUrl.hs

@@ -476,13 +476,13 @@ addWorkTree _ addunlockedmatcher u url file key mtmp = case mtmp of
 		maybeShowJSON $ JSONChunk [("key", serializeKey key)]
 		setUrlPresent key url
 		logChange key u InfoPresent
-		ifM (addAnnexedFile noci addunlockedmatcher file key mtmp)
+		ifM (addAnnexedFile addunlockedmatcher file key mtmp)
 			( do
 				when (isJust mtmp) $
 					logStatus key InfoPresent
 			, maybe noop (\tmp -> pruneTmpWorkDirBefore tmp (liftIO . removeWhenExistsWith R.removeLink)) mtmp
 			)
-	
+
 	-- git does not need to check ignores, because that has already
 	-- been done, as witnessed by the CannAddFile.
 	noci = CheckGitIgnore False

Command/Lock.hs

@@ -60,8 +60,7 @@ start si file key = ifM (isJust <$> isAnnexLink file)
 perform :: RawFilePath -> Key -> CommandPerform
 perform file key = do
 	lockdown =<< calcRepo (gitAnnexLocation key)
-	addLink (CheckGitIgnore False) file key
-		=<< withTSDelta (liftIO . genInodeCache file)
+	addSymlink file key =<< withTSDelta (liftIO . genInodeCache file)
 	next $ return True
   where
 	lockdown obj = do

Command/ReKey.hs

@@ -123,8 +123,7 @@ cleanup file newkey = do
 	ifM (isJust <$> isAnnexLink file)
 		( do
 			-- Update symlink to use the new key.
-			liftIO $ removeFile (fromRawFilePath file)
-			addLink (CheckGitIgnore False) file newkey Nothing
+			addSymlink file newkey Nothing
 		, do
 			mode <- liftIO $ catchMaybeIO $ fileMode <$> R.getFileStatus file
 			liftIO $ whenM (isJust <$> isPointerFile file) $