BUGFIX: hexlify segfault with zero-size argument
BUGFIX: hexlify segfault with zero-size argument

Airbitz/libbitcoin,swansontec/libbitcoin,libtetcoin/libtetcoin-consensus,libtetcoin/libtetcoin-consensus,Airbitz/libbitcoin,libmetrocoin/libmetrocoin-consensus,swansontec/libbitcoin,libtetcoin/libtetcoin-consensus,libmetrocoin/libmetrocoin-consensus,Airbitz/libbitcoin,libmetrocoin/libmetrocoin-consensus,GroestlCoin/libgroestlcoin,kaostao/libbitcoin,swansontec/libbitcoin,libmetrocoin/libmetrocoin-consensus,BWallet/libbitcoin,BWallet/libbitcoin,Airbitz/libbitcoin,libtetcoin/libtetcoin-consensus,BWallet/libbitcoin,libmetrocoin/libmetrocoin-consensus,GroestlCoin/libgroestlcoin,kaostao/libbitcoin,BWallet/libbitcoin,kaostao/libbitcoin,kaostao/libbitcoin,GroestlCoin/libgroestlcoin,libtetcoin/libtetcoin-consensus,GroestlCoin/libgroestlcoin,swansontec/libbitcoin