Conveniently link /root/.my.cnf on wiki servers

Since the mysql_backup::backup_remote class creates a
/root/.${name}_db.cnf file already, symlink root's .my.cnf to that
for more convenient `sudo -H mysql` operation on our wiki servers.

Change-Id: I0cda3c67926021ae468e711a5a8f3a4694dad735

modules/openstack_project/manifests/wiki.pp

@@ -69,6 +69,11 @@ class openstack_project::wiki (
     database_user     => $wg_dbuser,
     database_password => $wg_dbpassword,
   }
+  file { '/root/.my.cnf':
+    ensure  => link,
+    target  => '/root/.wiki_db.cnf',
+    require => Mysql_backup::Backup_remote['wiki'],
+  }
 
   if $bup_user != undef {
     include bup