Fix gcc warnings (for real).
Fix gcc warnings (for real).

libtetcoin/libtetcoin-explorer,GroestlCoin/libgroestlcoin-explorer,libmetrocoin/libmetrocoin-explorer,cancoin/libbitcoin-explorer,cancoin/libbitcoin-explorer,GroestlCoin/libgroestlcoin-explorer,libmetrocoin/libmetrocoin-explorer,tuomassiren/libbitcoin-explorer,tuomassiren/libbitcoin-explorer,libtetcoin/libtetcoin-explorer,GroestlCoin/libgroestlcoin-explorer