Add missing include for use of atoi.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@56836 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index c145888..382bba0 100644
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -17,6 +17,7 @@
 #include "clang/Basic/TargetInfo.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/APFloat.h"
+#include <cstdlib>
 
 using namespace clang;