fix build on some machines. thanks buildbot

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60175 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/Annotation.cpp b/lib/Support/Annotation.cpp
index 0e208e0..fdf6dc7 100644
--- a/lib/Support/Annotation.cpp
+++ b/lib/Support/Annotation.cpp
@@ -14,6 +14,7 @@
 #include "llvm/Support/Annotation.h"
 #include "llvm/Support/ManagedStatic.h"
 #include <map>
+#include <cstring>
 using namespace llvm;
 
 Annotation::~Annotation() {}  // Designed to be subclassed