add more things that do adds

[Lokathor]

I'm doing this on an arm32 device so I've already run all those tests and squared that away, but for arm64 we'll have to rely on the CI.

• The last two "add"
• "add across vector" (aka horizontal add)
• "add pairwise"

[Lokathor]

Alright, the current batch of errors should be fixed, except for the vek_leak feature no longer being needed.

I assume that we just delete that line now that it's stable, but I'll wait to let someone else confirm that.

[Amanieu]

Yes, you can just delete the vec_leak feature.

[Lokathor]

Out of time to work on the PR this morning, I will be back later today. If you could diagnose the ICE in the wasi build @Amanieu that would be quite helpful. I think it's just a flutter in the current nightly because this PR doesn't touch any wasi stuff.

[Amanieu]

cc @alexcrichton for the WASI CI failure

[alexcrichton]

Oh dear looks like something in rustc changed, feel free to drop it and I will investigate next monday

[alexcrichton]

I've fixed the wasi issue at rust-lang/rust#75316, and I'll circle back here to re-enable CI after that lands.