Create multilevel debug mode

llvm-svn: 139913
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 2751619..3f6bfd4 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -310,6 +310,16 @@
 #endif
 
 #ifdef _LIBCPP_DEBUG2
+#   if _LIBCPP_DEBUG2 == 0
+#       define _LIBCPP_DEBUG_LEVEL 1
+#   elif _LIBCPP_DEBUG2 == 1
+#       define _LIBCPP_DEBUG_LEVEL 2
+#   else
+#       error Supported values for _LIBCPP_DEBUG2 are 0 and 1
+#   endif
+#endif
+
+#ifdef _LIBCPP_DEBUG2
 #   include <__debug>
 #else
 #   define _LIBCPP_ASSERT(x, m) ((void)0)