[Patch x86-tip] Clean up the warning message about RCU not defined

[Jin Dongming <jin.dongming@np.css.fujitsu.com>]

(This fix is for commit 4765c1db84c73f775eb1822a009117cbae524e9e
   Titled "rcu-tiny: The Bloatwatch Edition, v6")

When the kernel is built, there is some message printed as
following:
    include/linux/rcupdate.h:80:7: \
        warning: "CONFIG_TINY_RCU" is not defined

So I did "grep _RCU .config" to search the information of "CONFIG_TINY_RCU"
in .config file and the result is listed as following:
    Command:
        grep _RCU .config
    Result:
        CONFIG_TREE_RCU=y
        # CONFIG_TREE_PREEMPT_RCU is not set
        # CONFIG_TINY_RCU is not set
        CONFIG_RCU_TRACE=y
        CONFIG_RCU_FANOUT=64
        # CONFIG_RCU_FANOUT_EXACT is not set
        CONFIG_TREE_RCU_TRACE=y
        # CONFIG_RCU_TORTURE_TEST is not set
        # CONFIG_RCU_CPU_STALL_DETECTOR is not set

Though the "WARNING" does not give impact to build kernel, I think
it should be cleaned up. And I made the patch for modifying it.
With this patch there is not any other warning message of
CONFIG_TINY_RCU and the kernel could be built successfully. And I
confirmed that the built kernel works well.

Signed-off-by: Jin Dongming <jin.dongming@np.css.fujitsu.com>
---
 include/linux/rcupdate.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index b2f1e10..fe5c560 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -77,7 +77,7 @@ extern int rcu_scheduler_active;
 
 #if defined(CONFIG_TREE_RCU) || defined(CONFIG_TREE_PREEMPT_RCU)
 #include <linux/rcutree.h>
-#elif CONFIG_TINY_RCU
+#elif defined(CONFIG_TINY_RCU)
 #include <linux/rcutiny.h>
 #else
 #error "Unknown RCU implementation specified to kernel configuration"
-- 
1.6.2.2