tools/liblockdep: Correct macro for WARN

As Peter Zijlstra pointed out, the varargs for WARN() are
optional, so we need to correctly handle the case where they
don't exist.

This would cause a compilation error.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1440479985-6696-2-git-send-email-sasha.levin@oracle.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

tools/lib/lockdep/uinclude/linux/kernel.h

@@ -23,7 +23,7 @@
 #define WARN_ON(x) (x)
 #define WARN_ON_ONCE(x) (x)
 #define likely(x) (x)
-#define WARN(x, y, z) (x)
+#define WARN(x, y...) (x)
 #define uninitialized_var(x) x
 #define __init
 #define noinline