checkasm helper for rust

It is a port of the dav1d checkasm harness to rust.

Usage

``` rust

[cfg(test)]

mod test { use checkasm::declarefn; use std::ffi::cvoid;

extern fn variant_avx2(a: *mut u8, len: usize);
extern fn variant_avx512(a: *mut u8, len: usize);

declare_fn { check_variant(a: *mut u8, len: usize) };

#[test]
fn variant() {
    let mut buf = vec![0u8; 128];

    check_variant(variant_avx512 as *mut c_void, buf.as_mut_ptr(), buf.len());
}

} ```

Status