[Wallet] Add parameter interaction between -disablewallet and -staking

[aaronm-cloudtek]

As title

See #158

[Mrs-X]

Concept ACK with a little Nit, the same #ifdef exists already here:
https://github.com/PIVX-Project/PIVX/blob/master/src/init.cpp#L757-L759
so I'd move yours down there, e.g.:

    setvbuf(stdout, NULL, _IOLBF, 0); /// ***TODO*** do we still need this after -printtoconsole is gone?

    // Staking needs a CWallet instance, so make sure wallet is enabled
#ifdef ENABLE_WALLET
    bool fDisableWallet = GetBoolArg("-disablewallet", false);
    if (fDisableWallet) {
#endif
        if (SoftSetBoolArg("-staking", false))
            LogPrintf("AppInit2 : parameter interaction: wallet functionality not enabled -> setting -staking=0\n");
#ifdef ENABLE_WALLET
    }
#endif

    nConnectTimeout = GetArg("-timeout", DEFAULT_CONNECT_TIMEOUT);

[aaronm-cloudtek]

Thanks, PR updated

[Mrs-X]

utACK 43899e1