rbtree: include rcu.h

Since commit c1adf20 ("Introduce rb_replace_node_rcu()")
rbtree_augmented.h uses RCU related data structures but does not include
the header file.  It works as long as it gets somehow included before
that and fails otherwise.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: David Howells <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Sebastian Andrzej Siewior

include/linux/rbtree_augmented.h

@@ -26,6 +26,7 @@
 
 #include <linux/compiler.h>
 #include <linux/rbtree.h>
+#include <linux/rcupdate.h>
 
 /*
  * Please note - only struct rb_augment_callbacks and the prototypes for

include/linux/rbtree_latch.h

@@ -35,6 +35,7 @@
 
 #include <linux/rbtree.h>
 #include <linux/seqlock.h>
+#include <linux/rcupdate.h>
 
 struct latch_tree_node {
 	struct rb_node node[2];