3abc41a45c
add missing feature in core/tests https://github.com/rust-lang/rust/pull/104265 introduced the `ip_in_core` feature. For some reason core tests seem to still build without that feature -- no idea how that is possible. Might be related to https://github.com/rust-lang/rust/issues/15702? I was under the impression that `pub use` with different stability doesn't actually work. That's why `intrinsics::transmute` is stable, for example. Either way, core tests fail to build in miri-test-libstd, and adding the feature fixes that. r? ```@thomcc```