[bug#68577] [PATCH v2 2/2] gnu: Add mullvadbrowser.

[Clément Lassieur]

I'll send an update for this patch : the build id is not the same as Tor
Browser's build id[0].

The Mullvad Browser one is 20240115174108.  I found it by going to
about:support, but if anyone knows a way to find it on the web, it'd
help me automate things a bit.

Another thing is about the way I package Mullvad Browser.  I wish to
inherit Tor Browser as much as I can, but the fact that they don't share
the build id, plus the fact that webRTC is supported by Mullvad and not
(yet) by Tor Browser means Mullvad users and Tor Browser users are not
in the same “bucket”[1].

To make things clear : our goal is for our Tor Browser users to be in
the same bucket as upstream Tor Browser users, and for our Mullvad
Browser users to be in the same bucket as Mullvad Browser upstream
users.

Thanks
Clément

[0]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=68676#19
[1]: 
https://forum.torproject.org/t/changing-operating-system-changes-browser-fingerprints/6345/3