Function indy_sys::crypto::indy_pack_message

#[no_mangle]
pub unsafe extern "C" fn indy_pack_message(
    command_handle: Handle, 
    wallet_handle: Handle, 
    message: BString, 
    message_len: u32, 
    receiver_keys: CString, 
    sender: CString, 
    cb: Option<ResponseSliceCB>
) -> Error