bug#15188: message should say what the accessibility bus is

[jidanni]

This message should say what the accessibility bus is. Some bus for old people?

     # su - nobody -c 'HOME=/tmp emacs -f w3m 
~jidanni/jidanni.org/location/directions/index.html'
     No directory, logging in with HOME=/

     ** (emacs:3345): WARNING **: Couldn't register with accessibility bus: Did 
not receive a reply. Possible causes include: the remote application did not 
send a reply, the message bus security policy blocked the reply, the reply 
timeout expired, or the network connection was broken.

Also the URL it is trying to reach, if any should be revealed.