This is used for the no-atomic-u64-test ci check that verifies that Tokio
works even if the AtomicU64 type is missing.
When increasing the nightly compiler version, you may need to regenerate this target using the following command:
rustc +nightly -Z unstable-options --print target-spec-json --target i686-unknown-linux-gnu | grep -v 'is-builtin' | sed 's/"max-atomic-width": 64/"max-atomic-width": 32/' > target-specs/i686-unknown-linux-gnu.json