Windows support by Ruben Van Boxem.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@142235 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/csetjmp b/include/csetjmp
index 2b8b81f..d0b2c07 100644
--- a/include/csetjmp
+++ b/include/csetjmp
@@ -34,7 +34,9 @@
 #include <__config>
 #include <setjmp.h>
 
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
+#endif
 
 #ifndef setjmp
 #define setjmp(env) setjmp(env)