Rename _LIBCPP_DEBUG2 to _LIBCPP_DEBUG.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@189140 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/www/debug_mode.html b/www/debug_mode.html
index a0b2e58..6474782 100644
--- a/www/debug_mode.html
+++ b/www/debug_mode.html
@@ -59,7 +59,7 @@
 <code>&lt;string&gt;</code>
 </p>
 </td>
-<td align="center"><!-- &#10003; --></td>
+<td align="center"> &#10003; </td>
 </tr>
 
 <tr>