RFC: Disable the ALSA driver by default.

[Luke Yelavich]

Hey folks.
One thing I have seen mentioned in many a discussion about speech-dispatcher in 
the recent past is about the state of the ALSA output driver, and its tendency 
to crash. I am wondering whether it is worth considering disabling the ALSA 
driver by default for now, and only building it if the user explicitly enables 
it at build time. For now, we have the libao driver as an alternative, and 
libao can be configured to use ALSA directly. Longer term, it would be better 
to have a direct ALSA driver, but until someone can take the time to fix its 
bugs, I'd rather users have a stable ALSA experience for now.

I haven't tested the ALSA driver myself recently, but I used to have regular 
crashers when I did use it, and that was on a single CPU/single core system. 
Given that the ALSA driver issues are likely threading related, I dare say it 
is much worse on multi-CPU/multi-core systems.

This is something I am considering for the 0.8.1 release. Any thoughts, or 
alternative suggestions are welcome.

Luke