[Ada] Bootstrapping mainline GNAT fails

[Robert Dewar]

 <<On the contrary - this is the most common arrangement for contributors
outside of ACT trying to build the Ada compiler; and it worked just
fine until the recent merge.
>>

That does not seem right to me. If you install a working version of GNAT you
have a gcc that handles C and Ada, and the most natural approach (and the
one we recommend) is that you use this gcc (C and Ada) to start the bootstrap
since that's what we have tested.

But anyway, as you say, this is not the issue in any case.