Firefox supported architectures

[Bryan Quigley]

Hi all,

It's been discussed a few times on IRC how Firefox gets stuck in
-proposed in dev releases because it doesn't compile for all the archs
on every Firefox release.   This also occurs for those same archs on
updates -  for example the most up-to-date Firefox release for ppc64el
Xenial is 52.

Can we drop Firefox building for some of the archs so that it's not
blocked on them? What archs do we really care about having Firefox on?

Currently building:amd64, arm64, i386
Currently failing: armhf, ppc64el,  armhf

Thoughts?
Bryan

* Latest build fails related to rust on ppc64el.   Check out rmadison
firefox for more (I believe it is accurate)