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
{
    std::string escaped = arg;
    ReplaceAll(escaped, "'", "'\"'\"'");
    return "'" + escaped + "'";
}
#endif
#if HAVE_SYSTEM
void runCommand(const std::string& strCommand)
{
    if (strCommand.empty()) return;
#ifndef WIN32
    int nErr = ::system(strCommand.c_str());
#else
    int nErr = ::_wsystem(std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>,wchar_t>().from_bytes(strCommand).c_str());
#endif
    if (nErr)
        LogPrintf("runCommand error: system(%s) returned %d\n", strCommand, nErr);
}
#endif
void SetupEnvironment()