Re: meson -Drust=enabled fails on macOS without GNU sed

> I think it's due to e509b5b8be (rust: support for Windows, 2025-10-15)
> [relevant folks CC'd], where we assume sed can take "-s" (which AFAICT
> is a GNU extension). But perhaps "-n" was intended with a "p" flag on
> the substitution?
>
> I've been building with Rust enabled on Gentoo now for a minute and
> haven't hit any issues, but that's perhaps because the command is
> running with "-s" and not working as intended (yet still producing the
> expected results).
>
> The relevant snippet is this (reformatted slightly by GMail, apologies):
>
> case "$(cargo -vV | sed -s 's/^host: \(.*\)$/\1/')" in
>   *-windows-*) LIBNAME=gitcore.lib;;
>   *) LIBNAME=libgitcore.a;;
> esac
>
> but "cargo -vV" produces something like
>
> cargo 1.89.0 (c24e10642 2025-06-23)
> [...]
> host: x86_64-apple-darwin
>
> (on my older system, on which I haven't tried the build; the failure
> is on my newer system with close-enough-to-the-same output). I'm sure
> you can see why I don't understand why we need GNU's "-s" ("consider
> files as separate rather than as a single, continuous long stream")
> here?