[BLOCK] Add request_queue_t and mark it deprecated

Andrew thinks I should be nice and allow outside code to at least just
compile, so add the request_queue_t typedef back and mark it deprecated.
It'll warn people that this type is going away soonish.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4be37de..a1c96d9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -37,6 +37,7 @@
 struct scsi_ioctl_command;
 
 struct request_queue;
+typedef struct request_queue request_queue_t __deprecated;
 struct elevator_queue;
 typedef struct elevator_queue elevator_t;
 struct request_pm_state;