Firefox 52's end of life, packaging Icecat 60

["Clément Lassieur" <clement@lassieur.org>]

Hello,

As this blog article[1] says, Firefox 52's end of life will happen on
August 28, 2018.  That is, in 47 days.  I imagine that by that time
Icecat 60 will be released, but it seems that we are pretty far from
being able to package it, because of the Rust packages that are needed.
There might be other technical difficulties that I'm not aware of,
though.

Is there any plan in this regard?  Maybe, as a first step, we should
list the required dependencies so that people can pick them up?  My
understanding of that article[2] is that the top level dependencies are
listed in Cargo.toml[3].

What is the current state of the Rust build system (cargo-build-system)?
Is there anything blocking that would prevent its use?  I'm asking
because I see very few packages in gnu/packages/rust.scm.

Thank you,
Clément

[1]: https://blog.mozilla.org/futurereleases/2018/01/11/announcing-esr60-policy-engine/
[2]: https://developer.mozilla.org/en-US/Firefox/Building_Firefox_with_Rust_code
[3]: https://dxr.mozilla.org/mozilla-central/source/toolkit/library/rust/shared/Cargo.toml