narrow nix/ipc-channel/capstone deps to x86 targets

[fneddy]

The cargo::unused_dependencies lint was recently added to Cargo and defaults to warn. Because bootstrap sets CARGO_BUILD_WARNINGS=deny for in-tree builds, this new default warning becomes a hard error.

This change silence the lint the same way we already do in other places.

[RalfJung]

Why would we want to have unused dependencies in Miri?

[fneddy]

ohh i forgot to put that in the commit. because capstone and nix are used only on x86 targets

miri/src/shims/native_lib/mod.rs

Lines 21 to 29 in 2f577e1

	#[cfg_attr(
	not(all(
	target_os = "linux",
	target_env = "gnu",
	any(target_arch = "x86", target_arch = "x86_64")
	)),
	path = "trace/stub.rs"
	)]
	pub mod trace;

[RalfJung]

Is it not possible to restrict these dependencies to only those targets then?

[RalfJung]

I assume this

miri/Cargo.toml

Line 43 in 2f577e1

[target.'cfg(target_os = "linux")'.dependencies]

just needs to be restricted to "x86 only". (And GNU only apparently.)

[RalfJung]

Thanks :)