mutex: make 0/1 FIO_MUTEX_LOCKED and FIO_MUTEX_UNLOCKED

Makes the API look cleaner.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/backend.c b/backend.c
index 9cc8dbc..e41e8f1 100644
--- a/backend.c
+++ b/backend.c
@@ -1620,7 +1620,7 @@
 
 	setup_disk_util();
 
-	disk_thread_mutex = fio_mutex_init(0);
+	disk_thread_mutex = fio_mutex_init(FIO_MUTEX_LOCKED);
 
 	ret = pthread_create(&disk_util_thread, NULL, disk_thread_main, NULL);
 	if (ret) {
@@ -1661,10 +1661,10 @@
 		setup_log(&agg_io_log[DDIR_WRITE], 0);
 	}
 
-	startup_mutex = fio_mutex_init(0);
+	startup_mutex = fio_mutex_init(FIO_MUTEX_LOCKED);
 	if (startup_mutex == NULL)
 		return 1;
-	writeout_mutex = fio_mutex_init(1);
+	writeout_mutex = fio_mutex_init(FIO_MUTEX_UNLOCKED);
 	if (writeout_mutex == NULL)
 		return 1;