Fix double_sha256 with no native support and no data to hash
Fix double_sha256 with no native support and no data to hash

martindale/RelayNode,arnuschky/RelayNode,TheBlueMatt/RelayNode,danoctavian/RelayNode,BitcoinRelayNetwork/RelayNode,danoctavian/RelayNode,martindale/RelayNode,arnuschky/RelayNode,BitcoinRelayNetwork/RelayNode,BitcoinRelayNetwork/RelayNode,TheBlueMatt/RelayNode