Work on Windows port by Ruben Van Boxem

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@140728 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/cwchar b/include/cwchar
index ce71782..0a67fe8 100644
--- a/include/cwchar
+++ b/include/cwchar
@@ -106,6 +106,9 @@
 #include <__config>
 #include <cwctype>
 #include <wchar.h>
+#if _WIN32
+#include <support/win32/support.h> // pull in *swprintf defines
+#endif // _WIN32
 
 #pragma GCC system_header