Add a Last Updated field to the C++ status page

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74387 91177308-0d34-0410-b5e6-96231b3b80d8

www/cxx_status.html

@@ -24,6 +24,7 @@
 <!--*************************************************************************-->
 <h1>C++ Support in Clang</h1>
 <!--*************************************************************************-->
+<p>Last updated: $Date$</p>
 
 <p>
 This page tracks the status of C++ support in Clang.<br>