Fix check-cfg-related and rust-lld-related CI failures (#1110)

Cargo.toml

@@ -63,5 +63,11 @@ members = [
 missing_debug_implementations = "warn"
 rust_2018_idioms = "warn"
 single_use_lifetimes = "warn"
+unexpected_cfgs = { level = "warn", check-cfg = [
+  'cfg(crossbeam_loom)',
+  'cfg(crossbeam_no_atomic)',
+  'cfg(crossbeam_sanitize)',
+  'cfg(crossbeam_sanitize_thread)',
+] }
 unreachable_pub = "warn"
 # unsafe_op_in_unsafe_fn = "warn" # Set at crate-level instead since https://github.com/rust-lang/rust/pull/100081 is not available on MSRV

ci/careful.sh

@@ -3,6 +3,9 @@ set -euxo pipefail
 IFS=$'\n\t'
 cd "$(dirname "$0")"/..
 
-export RUSTFLAGS="${RUSTFLAGS:-} -Z randomize-layout"
+# TODO: Once cargo-careful's bug (https://github.com/RalfJung/cargo-careful/issues/31) is fixed,
+# stop reverting back to the system's default linker, instead of rust-lld, which became the new 
+# default on linux recently (nightly-2024-05-18 and onwards).
+export RUSTFLAGS="${RUSTFLAGS:-} -Z randomize-layout -Z linker-features=-lld"
 
 cargo careful test --all --all-features --exclude benchmarks -- --test-threads=1