Windows support by Ruben Van Boxem.

llvm-svn: 142235
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 073458b1ab5489dce6f2ec789889c377b690ccf4
diff --git a/include/codecvt b/include/codecvt
index 86fdc72..6c44e34 100644
--- a/include/codecvt
+++ b/include/codecvt
@@ -55,7 +55,9 @@
 #include <__config>
 #include <__locale>
 
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
+#endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD