On my Linux Mint 19.1:
```bash
$ umask
0022
```

After the first run of `bitcoin-qt -sysperm=false` the `0700` permissions are expected for both the datadir (`~/.bitcoin`) and the walletdir (`~/.bitcoin/wallets`).

Actually, the directories are created with such access permissions:
```bash
$ stat ~/.bitcoin | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
$ stat ~/.bitcoin/wallets | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
```

Refs:
- #4286
- #13371
- #13389

NOTE: reading through the initial PR #4286 makes me think it was controversial. Is it a better and simpler way to just get rid of `-sysperm` option? I believe a user who needs this option can easily run `chown` command.
peer_connect_timeout = args.GetIntArg("-peertimeout", DEFAULT_PEER_CONNECT_TIMEOUT);
    if (peer_connect_timeout <= 0) {
        return InitError(Untranslated("peertimeout must be a positive integer."));
    }
    
    
    if (args.IsArgSet("-blockmintxfee")) {
        if (!ParseMoney(args.GetArg("-blockmintxfee", ""))) {
            return InitError(AmountErrMsg("blockmintxfee", args.GetArg("-blockmintxfee", "")));
        }
    }
    nBytesPerSigOp = args.GetIntArg("-bytespersigop", nBytesPerSigOp);
    if (!g_wallet_init_interface.ParameterInteraction()) return false;
    
    SetMockTime(args.GetIntArg("-mocktime", 0)); 
    if (args.GetBoolArg("-peerbloomfilters", DEFAULT_PEERBLOOMFILTERS))
        nLocalServices = ServiceFlags(nLocalServices | NODE_BLOOM);
    if (args.GetIntArg("-rpcserialversion", DEFAULT_RPC_SERIALIZE_VERSION) < 0)
        return InitError(Untranslated("rpcserialversion must be non-negative."));
    if (args.GetIntArg("-rpcserialversion", DEFAULT_RPC_SERIALIZE_VERSION) > 1)
        return InitError(Untranslated("Unknown rpcserialversion requested."));
    if (args.GetBoolArg("-reindex-chainstate", false)) {
        
        if (args.GetBoolArg("-coinstatsindex", DEFAULT_COINSTATSINDEX)) {
            return InitError(_("-reindex-chainstate option is not compatible with -coinstatsindex. Please temporarily disable coinstatsindex while using -reindex-chainstate, or replace -reindex-chainstate with -reindex to fully rebuild all indexes."));
        }
        if (g_enabled_filter_types.count(BlockFilterType::BASIC)) {
            return InitError(_("-reindex-chainstate option is not compatible with -blockfilterindex. Please temporarily disable blockfilterindex while using -reindex-chainstate, or replace -reindex-chainstate with -reindex to fully rebuild all indexes."));
        }
        if (args.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {