Implement parsing and semantic checking of the 'mutable' keyword.
Thanks to Doug for the review. Actual effects of mutable to follow.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59331 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/www/cxx_status.html b/www/cxx_status.html
index f4e3402..c8b8d57 100644
--- a/www/cxx_status.html
+++ b/www/cxx_status.html
@@ -607,7 +607,7 @@
   <td></td>

   <td></td>

   <td></td>

-  <td>No parser support for mutable members, using declarations, or templates.</td>

+  <td>No parser support for using declarations, or templates.</td>

 </tr>

 <tr>

   <td>&nbsp;&nbsp;9.3 [class.mfct]</td>