committed: merge with libada-branch

[Arnaud Charlet]

> Well it is not working on powerpc-apple-darwin where Ada is not 
> available
> and does not work either (a different bug already filed).

If Ada does not work, obviousely you can't expect libada to work.

The proper approach here is to disable ada when configuring.
Now, if you're really lazy and don't want to specify the list of languages
you want to enable, then you can use --disable-libada, as documented :-)

Arno