Implement utmp for solarish targets

[GrayJack]

I followed these references:

https://github.com/illumos/illumos-gate/blob/4e0c5eff9af325c80994e9527b7cb8b3a1ffd1d4/usr/src/head/utmpx.h
https://github.com/illumos/illumos-gate/blob/4e0c5eff9af325c80994e9527b7cb8b3a1ffd1d4/usr/src/head/utmp.h

[rust-highfive]

r? @gnzlbg

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[glaubitz]

@GrayJack Can you fix the spelling error "solarish" => "solaris"?

[GrayJack]

@glaubitz I did used that intentionally, since internally the module is called solarish, probably because there more than one platform that have the same base (Oracle Solaris and Illumos).

I think there was a discussion to have a illumos target for Rust, probably cause there is enough differences between both nowadays.

But if that is really gonna be a problem, sure, I can change

[gnzlbg]

cc @jasonbking @bgermann

[jasonbking]

Another community member coined the term -- while there's a common heritage between illumos and Solaris, they've been separate projects for well over a decade now and have diverged in some areas so it's similar to the BSDs in that sense (a lot of things in common, and a number of things that are different). As to the change itself, it looks good to me.

[bgermann]

Looks good to me, too.

[gnzlbg]

@bors: r+

[bors]

📌 Commit 54283f9 has been approved by gnzlbg

[bors]

⌛ Testing commit 54283f9 with merge 581ba35...

[bors]

☀️ Test successful - checks-cirrus-freebsd-10, checks-cirrus-freebsd-11, checks-cirrus-freebsd-12, status-azure
Approved by: gnzlbg
Pushing 581ba35 to master...