rbtree/test: move rb_node to the middle of the test struct

Avoid making the rb_node the first entry to catch some bugs around NULL
checking the rb_node.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/rbtree_test.c

@@ -8,8 +8,8 @@
 #define CHECK_LOOPS 100
 
 struct test_node {
-	struct rb_node rb;
 	u32 key;
+	struct rb_node rb;
 
 	/* following fields used for testing augmented rbtree functionality */
 	u32 val;