bad bindings for weird alignments

I'm getting a fail test for the Kangaroo Twelve hash function. The thing has quite some weird alignments depending on the architecture targeted so I'm not surprised (had similar issues when trying to write the bindings by hand):

#[test]
fn bindgen_test_layout_KangarooTwelve_Instance() {
    assert_eq!(
        ::std::mem::size_of::<KangarooTwelve_Instance>(),
        456usize,
        concat!("Size of: ", stringify!(KangarooTwelve_Instance))
    );

to replicate the problem:

1. git clone https://github.com/mimoo/xkcp-sys.git
2. git checkout bindgen
3. cargo build or cargo test
4. to check the .h note the OUT_DIR in the failed test: /home/vagrant/work/xkcp-sys/target/debug/build/<sys-xkcp-OUT_DIR>/out/XKCP/bin/generic64/libkeccak.a.headers/

if you check the .h files you'll see this something like this:

#define KeccakP1600_stateSizeInBytes    200
#define KeccakP1600_stateAlignment      8

// ...

typedef struct {
    KeccakWidth1600_12rounds_SpongeInstance queueNode;
    KeccakWidth1600_12rounds_SpongeInstance finalNode;
    size_t fixedOutputLength;
    size_t blockNumber;
    unsigned int queueAbsorbedLen;
    KangarooTwelve_Phases phase;
} KangarooTwelve_Instance;

// ...

KCP_DeclareSpongeStructure(KeccakWidth1600_12rounds, KeccakP1600_stateSizeInBytes, KeccakP1600_stateAlignment)
    KCP_DeclareSpongeFunctions(KeccakWidth1600_12rounds)

// ...

#define KCP_DeclareSpongeStructure(prefix, size, alignment) \
    ALIGN(alignment) typedef struct prefix##_SpongeInstanceStruct { \
        unsigned char state[size]; \
        unsigned int rate; \
        unsigned int byteIOIndex; \
        int squeezing; \
    } prefix##_SpongeInstance;

Reproduce the failure in xkcp-sys on the bindgen branch with cargo build or cargo test, then inspect the generated headers under OUT_DIR and the bindgen_test_layout_KangarooTwelve_Instance assertion. Compare the C alignment and structure declarations with the generated Rust layout; done means the reported layout failure is resolved for the affected target architectures.