Update clang to r339409.

Change-Id: I800772d2d838223be1f6b40d490c4591b937fca2
diff --git a/linux-x64/clang/include/llvm/Analysis/DominanceFrontierImpl.h b/linux-x64/clang/include/llvm/Analysis/DominanceFrontierImpl.h
index dffb2e0..99224c0 100644
--- a/linux-x64/clang/include/llvm/Analysis/DominanceFrontierImpl.h
+++ b/linux-x64/clang/include/llvm/Analysis/DominanceFrontierImpl.h
@@ -21,6 +21,7 @@
 #include "llvm/ADT/GraphTraits.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Analysis/DominanceFrontier.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/GenericDomTree.h"
 #include "llvm/Support/raw_ostream.h"