Function wcsncasecmp 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn wcsncasecmp(
    s1: *const wchar_t,
    s2: *const wchar_t,
    n: size_t,
) -> c_int

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/wcsncasecmp.html.