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.
: m_control_host{control_host},
      m_interrupt{interrupt},
      m_control_sock{std::make_unique<Sock>(INVALID_SOCKET)},
      m_transient{true}
{
}
Session::~Session()
{
    LOCK(m_mutex);
    Disconnect();
}
bool Session::Listen(Connection& conn)
{
    try {
        LOCK(m_mutex);
        CreateIfNotCreatedAlready();
        conn.me = m_my_addr;
        conn.sock = StreamAccept();
        return true;
    } catch (const std::runtime_error& e) {
        Log("Error listening: %s", e.what());
        CheckControlSock();
    }
    return false;
}
bool Session::Accept(Connection& conn)