btrfs: remove unused function prototypes

function prototypes without a body

Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/transaction.h

@@ -101,11 +101,8 @@ struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid);
 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 				     struct btrfs_root *root);
-int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
-			    struct btrfs_root *root);
 
 int btrfs_add_dead_root(struct btrfs_root *root);
-int btrfs_drop_dead_root(struct btrfs_root *root);
 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly);
 int btrfs_clean_old_snapshots(struct btrfs_root *root);
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,