rbtree: allow tests to run as builtin

No reason require rbtree test code to be a module, allow it to be builtin
(streamlines my development process)

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Reviewed-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig.debug

@@ -1461,7 +1461,7 @@ config BACKTRACE_SELF_TEST
 
 config RBTREE_TEST
 	tristate "Red-Black tree test"
-	depends on m && DEBUG_KERNEL
+	depends on DEBUG_KERNEL
 	help
 	  A benchmark measuring the performance of the rbtree library.
 	  Also includes rbtree invariant checks.