python3.9: Add arc-linux-gnu triplet

[Alexey Brodkin]

On Wed, 11 Aug 2021 15:34:09 +0300 Alexey Brodkin <Alexey.Brodkin at synopsys.com> wrote: 
> Source: python3.9 
> Severity: normal 
> Tags: patch upstream 
> 
> Dear Maintainer, 
> 
> There's a new triplet for ARCv2 processors "arc-linux-gnu" 
> defined here https://wiki.debian.org/Multiarch/Tuples. 
> 
> With addition of this triplet to Python3 it becomes buildable for ARC. 
> Attaching a simple diff that implements proposed change. 
> 
> -- System Information: 
> Debian Release: bullseye/sid 
>   APT prefers focal-updates 
>   APT policy: (500, 'focal-updates'), (500, 'focal-security'), (500, 'focal-proposed'), (500, 'focal'), (100, 'focal-backports')
> Architecture: amd64 (x86_64) 
> 
> Kernel: Linux 5.4.72-microsoft-standard-WSL2 (SMP w/12 CPU cores) 
> Locale: LANG=C.UTF-8, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE=C.UTF-8 (charmap=UTF-8) 
> Shell: /bin/sh linked to /usr/bin/dash 
> Init: unable to detect 

Ping!

-Alexey