committed: merge with libada-branch

[Arnaud Charlet]

> My worry is that the multilib logic won't even be able to handle that.
> It is insanely fragile.  (Specifically, I do not think it can handle
> any recursive make invocation that transfers control to a sibling
> directory.)
> 
> Nathanael Nerode is probably the best person to ask about how it
> works, and I certainly may be wrong about this.

OK, to be discussed further.
Clearly, if multilib is as fragile as you are describing it, it
also needs to be improved.

> My primary interest in this entire issue is because I want global
> consistency, and to the extent that you and the other Ada maintainers
> are willing to work toward global consistency I'm willing to meet
> you somewhere in the middle, including familiarizing myself with the
> current structure of the library.  But note that global consistency
> most definitely does mean that the library sources move out of the gcc
> subdirectory, since all other languages do that.

I agree that global consistency is a general good goal.
Of course each language has its own specificities and requirements that are
not the same across languages, so it's not a black or white situation as
I'm sure you'll agree.

Things are clearly going in the right direction in my view, and I
believe the general goals are mainly shared. There are lots of
details to work out, so these things take time and are pretty delicate.

Arno