mkfs.bfs: fix block device open race

This fix makes mkfs.bfs also to detect if block device is busy, and warn if
the device is misaligned.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

disk-utils/mkfs.bfs.c

@@ -187,7 +187,7 @@ int main(int argc, char **argv)
 	if (!S_ISBLK(statbuf.st_mode))
 		errx(EXIT_FAILURE, _("%s is not a block special device"), device);
 
-	fd = open(device, O_RDWR | O_EXCL);
+	fd = open_blkdev_or_file(&statbuf, device, O_RDWR);
 	if (fd < 0)
 		err(EXIT_FAILURE, _("cannot open %s"), device);