I'd like to remove the align cargo feature (or make it a dummy), and automatically use repr(align) if the Rust version is new enough (newer than Rust 1.25.0).

In particular, I'd like for libc to not expose the C APIs that use repr(align) if repr(align) is not available anymore. This would be a breaking change, but using these APIs without the proper alignment is undefined behavior anyways (unless one is super super super careful).

Users that want to use these APIs and are currently on Rust versions older than Rust 1.25.0 can either stick to an older libc version or upgrade to at least Rust 1.25.0.