Update clang to r339409.

Change-Id: I800772d2d838223be1f6b40d490c4591b937fca2
diff --git a/linux-x64/clang/include/llvm/Support/Host.h b/linux-x64/clang/include/llvm/Support/Host.h
index ddc5fa5..57c79c0 100644
--- a/linux-x64/clang/include/llvm/Support/Host.h
+++ b/linux-x64/clang/include/llvm/Support/Host.h
@@ -31,7 +31,7 @@
 #define BYTE_ORDER LITTLE_ENDIAN
 #endif
 #else
-#if !defined(BYTE_ORDER) && !defined(LLVM_ON_WIN32)
+#if !defined(BYTE_ORDER) && !defined(_WIN32)
 #include <machine/endian.h>
 #endif
 #endif