Windows support by Ruben Van Boxem.

llvm-svn: 142235
diff --git a/libcxx/include/map b/libcxx/include/map
index 886aecf..8bb7555 100644
--- a/libcxx/include/map
+++ b/libcxx/include/map
@@ -375,7 +375,9 @@
 #include <functional>
 #include <initializer_list>
 
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
+#endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD