The new definition of in6_addr:

pub struct in6_addr {
    pub s6_addr: [u8; 16],
    __align: [u32; 0],
}

Link: https://github.com/rust-lang-nursery/libc/blob/e7ff66ba3df6eb0d10953245a2a6fd2ecf082ccd/src/unix/mod.rs#L62

Means that it is now impossible to construct a value of type in6_addr from Rust, outside of the libc crate, since the __align field is private. I've had to fix libpnet to an old version of libc to work around this.