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/cmath b/include/cmath
index f8bc0df..bc3151b 100644
--- a/include/cmath
+++ b/include/cmath
@@ -301,7 +301,9 @@
 #include <math.h>
 #include <type_traits>
 
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
+#endif
 
 // signbit