Fix compile issue on some platforms. (#870)
Fix compile issue on some platforms. (#870)

Compilation was failing when on native windows.
Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Bitcoin-com/BUcash,Justaphf/BitcoinUnlimited,Justaphf/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Justaphf/BitcoinUnlimited,Bitcoin-com/BUcash,Bitcoin-com/BUcash,BitcoinUnlimited/BitcoinUnlimited,BitcoinUnlimited/BitcoinUnlimited,Bitcoin-com/BUcash,Justaphf/BitcoinUnlimited,Bitcoin-com/BUcash,BitcoinUnlimited/BitcoinUnlimited,Bitcoin-com/BUcash,BitcoinUnlimited/BitcoinUnlimited