stabs support in binutils, gcc, and gdb

[Arnaud Charlet]

> It would be helpful for Adacore to contribute the support upstream
> into the FSF tree, not only to make GNU Binutils more useful on AIX
> but to avoid others duplicating your work -- especially in
> incompatible ways.

Indeed.

> The large TOC feature (cmodel=large) is not used by default and the
> TLS feature is not enabled by default, so HEAD probably should
> bootstrap with your private changes to Binutils. TLS tests for
> assembler support, so that should fail with Binutils.
> 
> I had wanted your feedback about TLS within Ada before enabling the
> configuration test by default, but that apparently will not be
> possible with the way that Adacore's development model on AIX has
> diverged.

We haven't done any work to support TLS in gnu as/ld on AIX (other
than ignore these sections for now to avoid generating hard errors), so
enabling TLS in GCC would indeed cause some troubles, although we don't
use TLS directly in GNAT.

Arno