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.
assert(util::SettingsSpan(*includes).last_negated());
                use_conf_file = false;
            }
        }
        if (use_conf_file) {
            std::string chain_id = GetChainName();
            std::vector<std::string> conf_file_names;
            auto add_includes = [&](const std::string& network, size_t skip = 0) {
                size_t num_values = 0;
                LOCK(cs_args);
                if (auto* section = util::FindKey(m_settings.ro_config, network)) {
                    if (auto* values = util::FindKey(*section, "includeconf")) {
                        for (size_t i = std::max(skip, util::SettingsSpan(*values).negated()); i < values->size(); ++i) {
                            conf_file_names.push_back((*values)[i].get_str());
                        }
                        num_values = values->size();
                    }
                }
                return num_values;
            };
            
            
            const size_t chain_includes = add_includes(chain_id);
            const size_t default_includes = add_includes({});
            for (const std::string& conf_file_name : conf_file_names) {
                std::ifstream conf_file_stream{GetConfigFile(fs::PathFromString(conf_file_name))};
                if (conf_file_stream.good()) {
                    if (!ReadConfigStream(conf_file_stream, conf_file_name, error, ignore_invalid_keys)) {
                        return false;