Allow -Zconfig-profile for rust 1.43.0

[Keruspe]

While -Zconfig-profile doesn't do anything since the stabilisation of this feature, rust 1.43.0 still passes this to cargo, so allow (but ignore) it to allow rust 1.43.0 to build itself.

Fixes rust-lang/rust#69975 once cargo gets updated in the beta branch

[rust-highfive]

r? @alexcrichton

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[rust-highfive]

⚠️ Warning ⚠️

• Pull requests are usually filed against the master branch for this repo, but this one is against rust-1.43.0. Please double check that you specified the right target!

[aleksator]

Isn't it backwards? I'd think that since the flag was stabilized, a PR to rustc should be opened instead to stop sending this flag.

[Keruspe]

@aleksator rustbuild from rust 1.43.0 still needs to pass this flag when building from 1.42.0 (which it does, by default). The goal here is just not to refuse the flag, only for this release, to enable a smooth transition and be able to also build rust 1.43.0 using itself, which is something distribution packages usually do.

The alternative is to conditionally drop the argument in rustbuild in downstream packages, which can be done if preferred. We just usually submit what we believe to be an acceptable solution upstream first

[Mark-Simulacrum]

We definitely shouldn't be filing this against Cargo, regardless -- if you want to file a patch against rust-lang beta branch then I can review that there (we already do some version detection on the bootstrap compiler, IIRC, so if this can fit into that I wouldn't be opposed to it). Otherwise, yeah, I would fix downstream.

[Keruspe]

Ok, closing this one then, will try to do this in rustbuild