speechd-el fails when brltty is not available

[Christopher Brannon]

I started speechd-el with the following commands:
(load-library "speechd-speak")
(speechd-speak)

Here is what I get in my *Messages* buffer:

Loading /usr/share/emacs/site-lisp/speechd-el/speechd-speak.el (source)...done
brltty-connection-error: (file-error make client process failed connection 
refused :name brltty :buffer nil :host localhost :service 35751)
let*: mmanager--manager-message-blocks accessing a non-mmanager--manager
Error in post-command-hook: (error mmanager--manager-message-blocks accessing a 
non-mmanager--manager)
Error in pre-command-hook: (error mmanager--manager-busy-f accessing a 
non-mmanager--manager)

The "error in pre-command-hook" and "error in post-command-hook"
messages continue.  It's almost impossible to use any interactive
commands at this point.  I can't even terminate emacs gracefully.
I end up having to kill it from another console.

Removing brltty from speechd-out-active-drivers makes this issue go
away.  Any idea what is going on here?  I don't know the speechd-el code
very well, so all I can do is guess at this point.

-- Chris