xfs: remove unused struct declarations

After scratching my head looking for "xfs_busy_extent" I realized
it's not used; it's xfs_extent_busy, and the declaration for the
other name is bogus.  Remove that and a few others as well.

(struct xfs_log_callback is used, but the 2nd declaration is
unnecessary).
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_log_recover.h

@@ -42,7 +42,6 @@ typedef struct xlog_recover_item {
 	xfs_log_iovec_t		*ri_buf;	/* ptr to regions buffer */
 } xlog_recover_item_t;
 
-struct xlog_tid;
 typedef struct xlog_recover {
 	struct hlist_node	r_list;
 	xlog_tid_t		r_log_tid;	/* log's transaction id */

fs/xfs/xfs_log.h

@@ -124,7 +124,6 @@ struct xlog_ticket;
 struct xfs_log_item;
 struct xfs_item_ops;
 struct xfs_trans;
-struct xfs_log_callback;
 
 xfs_lsn_t xfs_log_done(struct xfs_mount *mp,
 		       struct xlog_ticket *ticket,

fs/xfs/xfs_trace.h

@@ -2245,7 +2245,6 @@ DEFINE_BTREE_CUR_EVENT(xfs_btree_overlapped_query_range);
 
 /* deferred ops */
 struct xfs_defer_pending;
-struct xfs_defer_intake;
 struct xfs_defer_ops;
 
 DECLARE_EVENT_CLASS(xfs_defer_class,

fs/xfs/xfs_trans.h

@@ -32,7 +32,6 @@ struct xfs_mount;
 struct xfs_trans;
 struct xfs_trans_res;
 struct xfs_dquot_acct;
-struct xfs_busy_extent;
 struct xfs_rud_log_item;
 struct xfs_rui_log_item;
 struct xfs_btree_cur;