block: remove bio_destructor_t

Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NBart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: NJens Axboe <axboe@fb.com>

include/linux/blk_types.h

@@ -16,7 +16,6 @@ struct block_device;
 struct io_context;
 struct cgroup_subsys_state;
 typedef void (bio_end_io_t) (struct bio *);
-typedef void (bio_destructor_t) (struct bio *);
 
 #ifdef CONFIG_BLOCK
 /*