fsck: fix racing between unlock/unlink and open

Process A	Process B	Process C
open()
[creates file]
lock()
[succeed]
		open()
		[open existing]
		lock()...
running()
close()
		[...succeed]
unlink()
		running()
				open()
				[creates file] {BAD!}
				lock()
				[succeed] {BAD!}
				running() {BAD!}
		close()

Cons: leaves empty (unlocked/harmless) .lock files in /run/fsck/
Signed-off-by: Yuriy M. Kaminskiy <yumkam@gmail.com>

disk-utils/fsck.c

@@ -410,7 +410,6 @@ static void unlock_disk(struct fsck_instance *inst)
 		printf(_("Unlocking %s.\n"), inst->lockpath);
 
 	close(inst->lock);			/* unlock */
-	unlink(inst->lockpath);
 
 	free(inst->lockpath);