Partial Windows port by Ruben Van Boxem

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@140328 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index 84a7ddd..6f98322 100644
--- a/include/__config
+++ b/include/__config
@@ -50,6 +50,10 @@
 #ifdef _WIN32
 #  define _LIBCPP_LITTLE_ENDIAN 1
 #  define _LIBCPP_BIG_ENDIAN    0
+// Compiler intrinsics (GCC or MSVC)
+#  if (defined(_MSC_VER) && _MSC_VER >= 1400) || (__GNUC__ >= 4 && __GNUC_MINOR__ > 3)
+#    define _LIBCP_HAS_IS_BASE_OF
+#  endif
 #endif  // _WIN32
 
 #if !defined(_LIBCPP_LITTLE_ENDIAN) || !defined(_LIBCPP_BIG_ENDIAN)
@@ -164,6 +168,10 @@
 #define _LIBCPP_HAS_NO_GENERALIZED_INITIALIZERS
 #endif
 
+#if __has_feature(is_base_of)
+#  define _LIBCP_HAS_IS_BASE_OF
+#endif
+
 // Objective-C++ features (opt-in)
 #if __has_feature(objc_arc)
 #define _LIBCPP_HAS_OBJC_ARC