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.
}
            const uint256 asmap_version = SerializeHash(asmap);
            LogPrintf("Using asmap version %s for IP bucketing\n", asmap_version.ToString());
        } else {
            LogPrintf("Using 16 prefix for IP bucketing\n");
        }
        
        assert(!node.netgroupman);
        node.netgroupman = std::make_unique<NetGroupManager>(std::move(asmap));
        
        assert(!node.addrman);
        uiInterface.InitMessage(_("Loading P2P addresses…").translated);
        if (const auto error{LoadAddrman(*node.netgroupman, args, node.addrman)}) {
            return InitError(*error);
        }
    }
    assert(!node.banman);
    node.banman = std::make_unique<BanMan>(gArgs.GetDataDirNet()  "banlist", &uiInterface, args.GetIntArg("-bantime", DEFAULT_MISBEHAVING_BANTIME));
    assert(!node.connman);
    node.connman = std::make_unique<CConnman>(GetRand<uint64_t>(),
                                              GetRand<uint64_t>(),
                                              *node.addrman, *node.netgroupman, args.GetBoolArg("-networkactive", true));
    assert(!node.fee_estimator);
     
     
    if (!ignores_incoming_txs) node.fee_estimator = std::make_unique<CBlockPolicyEstimator>(FeeestPath(args));
     
    for (const std::string port_option : {
        "-port",
        "-rpcport",