Meaning of "Builds libada directory"

[Duncan Sands]

$ ./configure --help | grep -i ada
  --enable-libada        Builds libada directory

There does not seem to be a libada directory in the
gdb sources, so what does this mean?  I came across
this while trying to work out what I need to turn on
in order to get Ada support in gdb (latest CVS).  In
fact gdb seems to know about Ada, but for some reason
Ada is not chosen when debugging Ada programs: I just
get

Current language:  auto; currently minimal

...

All the best,

Duncan.