[PATCH wwwdocs] Explicitly list powerpc64le-unknown-linux-gnu as a primary platform

[David Edelsohn]

On Mon, Jul 13, 2020 at 8:06 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> The intent was that this was implied by powerpc64-unknown-linux-gnu,
> but this not very obvious because of the ELFv1 vs ELFv2 ABI
> differences.

It's okay to _add_ PPC64LE without removing PPC64.  This is okay.

I'm not certain why it's useful to retroactively add the criterion to
GCC9 and GCC10, but whatever.

Thanks, David