[Mesa-dev] Mesa main repor branch clean-up

[Jason Ekstrand]

All,

At suggestion from several people on IRC, I've done a bit of house
cleaning of the main Mesa repo.  I created a new mesa/mesa-archive
repo and moved all of the stale feature branches to that repo and
removed them from mesa/mesa.  Many of those branches haven't seen a
commit in 10-20 years so all they're doing for most mesa devs is
adding clutter.

I left all the release branches since 7.8.  Dylan suggested I get rid
of those too but it seems like a good idea to leave them for archival
purposes.  If others think they should be removed, I'm happy to do
that.

If someone objects to moving stale branches to an archive repo, feel
free to say so and I can always put them back.

--Jason