Export the augmented rbtree helper functions

The augmented rbtree helper functions are not exported to modules right
now.

(We have started using augmented rbtrees in the upcoming version of
drbd.)
Signed-off-by: Andreas Gruenbacher <agruen@linbit.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/rbtree.c

@@ -315,6 +315,7 @@ void rb_augment_insert(struct rb_node *node, rb_augment_f func, void *data)
 
 	rb_augment_path(node, func, data);
 }
+EXPORT_SYMBOL(rb_augment_insert);
 
 /*
  * before removing the node, find the deepest node on the rebalance path
@@ -340,6 +341,7 @@ struct rb_node *rb_augment_erase_begin(struct rb_node *node)
 
 	return deepest;
 }
+EXPORT_SYMBOL(rb_augment_erase_begin);
 
 /*
  * after removal, update the tree to account for the removed entry
@@ -350,6 +352,7 @@ void rb_augment_erase_end(struct rb_node *node, rb_augment_f func, void *data)
 	if (node)
 		rb_augment_path(node, func, data);
 }
+EXPORT_SYMBOL(rb_augment_erase_end);
 
 /*
  * This function returns the first node (in sort order) of the tree.