Add a set of macros for using the new '[[[deprecated]]' attribute. No code changes (yet)

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@191625 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/__config b/include/__config
index 4d79d7f..dead4c6 100644
--- a/include/__config
+++ b/include/__config
@@ -571,12 +571,20 @@
 #  endif
 #endif  // _LIBCPP_STD_VER
 
+#if _LIBCPP_STD_VER > 11
+#define _LIBCPP_DEPRECATED [[deprecated]]
+#else
+#define _LIBCPP_DEPRECATED
+#endif
+
 #if _LIBCPP_STD_VER <= 11
 #define _LIBCPP_CONSTEXPR_AFTER_CXX11
 #define _LIBCPP_EXPLICIT_AFTER_CXX11
+#define _LIBCPP_DEPRECATED_AFTER_CXX11
 #else
 #define _LIBCPP_CONSTEXPR_AFTER_CXX11 constexpr
 #define _LIBCPP_EXPLICIT_AFTER_CXX11 explicit
+#define _LIBCPP_DEPRECATED_AFTER_CXX11 [[deprecated]]
 #endif
 
 #endif  // _LIBCPP_CONFIG