Add some missing #includes for GCC mainline, patch by Shantonu Sen!

llvm-svn: 48153
diff --git a/clang/Driver/SerializationTest.cpp b/clang/Driver/SerializationTest.cpp
index 552235b..37f2b69 100644
--- a/clang/Driver/SerializationTest.cpp
+++ b/clang/Driver/SerializationTest.cpp
@@ -23,7 +23,7 @@
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/Support/Streams.h"
 #include <fstream>
-
+#include <cstring>
 using namespace clang;
 
 //===----------------------------------------------------------------------===//