Macro compat_function

macro_rules! compat_function {
    (
        originally_defined_for($cfg:meta);

        $(#[$attrs:meta])*
        pub unsafe fn $name:ident($($arg_names:ident: $arg_types:ty),* $(,)?) -> $ret:ty $body:block
    ) => { ... };
}

Internal helper macro which defines compatibility shims for C API functions, deferring to a re-export when that’s available.