Function glk::gidispatch_set_retained_registry

#[no_mangle]
pub extern "C" fn gidispatch_set_retained_registry(
    regi: Option<unsafe extern "C" fn(array: *mut c_void, len: glui32, typecode: *const c_char) -> gidispatch_rock_t>, 
    unregi: Option<unsafe extern "C" fn(array: *mut c_void, len: glui32, typecode: *const c_char, objrock: gidispatch_rock_t)>
)