fixes a buildbot failure.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@167934 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGBlocks.cpp b/lib/CodeGen/CGBlocks.cpp
index 33f6eeb..69449b1 100644
--- a/lib/CodeGen/CGBlocks.cpp
+++ b/lib/CodeGen/CGBlocks.cpp
@@ -21,6 +21,7 @@
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/DataLayout.h"
 #include <algorithm>
+#include <cstdio>
 
 using namespace clang;
 using namespace CodeGen;