The `make install` script, which most users would run via `sudo` to install into `/usr/local`, will use the current umask of the root user when creating certain files and directories. If one uses a restrictive umask by default (e.g. `umask 077`), this means that only the root user will be able to use the full Bitcoin package.

**Expected behavior**

The install script creates all directories and files, including man pages, etc., with permissions `644` / `755`.

**Actual behavior**

Certain folders are created using the default umask, e.g.:

- /usr/local/share/man/man1/
- /usr/local/lib/pkgconfig/
- [...]

This means that only root can access files in these folders and other users won't be able to read the man pages (for example).

**To reproduce**

```bash
$ ./autogen.sh
$ make
$ sudo -iu root
% umask 077
% make install
```

**System information**

OS: Linux
bitcoind version: HEAD
{
    fs::path path;
    if (!GetSettingsPath(&path,  false)) {
        return true; 
    }
    LOCK(cs_args);
    m_settings.rw_settings.clear();
    std::vector<std::string> read_errors;
    if (!util::ReadSettings(path, m_settings.rw_settings, read_errors)) {
        SaveErrors(read_errors, errors);
        return false;
    }
    for (const auto& setting : m_settings.rw_settings) {
        KeyInfo key = InterpretKey(setting.first); 
        if (!GetArgFlags('-' + key.name)) {
            LogPrintf("Ignoring unknown rw_settings value %s\n", setting.first);
        }
    }
    return true;
}
bool ArgsManager::WriteSettingsFile(std::vector<std::string>* errors, bool backup) const