Since ObjCARC has been refactored into its own library with its own declaration header, we need to include the declaration header alongside Scalar.h in BackendUtil.

llvm-svn: 173648
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index b938aac..6d42df5 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -34,6 +34,7 @@
 #include "llvm/Transforms/IPO.h"
 #include "llvm/Transforms/IPO/PassManagerBuilder.h"
 #include "llvm/Transforms/Instrumentation.h"
+#include "llvm/Transforms/ObjCARC.h"
 #include "llvm/Transforms/Scalar.h"
 using namespace clang;
 using namespace llvm;