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.
}) {
        if (args.IsArgSet(port_option)) {
            const std::string port = args.GetArg(port_option, "");
            uint16_t n;
            if (!ParseUInt16(port, &n) || n == 0) {
                return InitError(InvalidPortErrMsg(port_option, port));
            }
        }
    }
    for (const std::string port_option : {
        "-i2psam",
        "-onion",
        "-proxy",
        "-rpcbind",
        "-torcontrol",
        "-whitebind",
        "-zmqpubhashblock",
        "-zmqpubhashtx",
        "-zmqpubrawblock",
        "-zmqpubrawtx",
        "-zmqpubsequence",
    }) {
        for (const std::string& socket_addr : args.GetArgs(port_option)) {
            std::string host_out;
            uint16_t port_out{0};
            if (!SplitHostPort(socket_addr, port_out, host_out)) {
                return InitError(InvalidPortErrMsg(port_option, socket_addr));
            }
        }
    }